How do I stop the main thread in the android ViewModelScope coltin?

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import PACKAGE.smbclient2.databinding.ActivityMainBinding

classMainActivity:AppCompatActivity(){

    //////////////////////////////////////////////
    valDOMAIN: String="192.168.1.1"
    val SMBROOT: String="/SMB/SERVER/FILE/"
    val USER: String="FOO"
    val PASSWORD: String="BAR"
    //////////////////////////////////////////////

    override fun onCreate (savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val binding = ActivityMainBinding.inflate (layoutInflater)
        setContentView (binding.root)

        // prepare for connecting SMB server
        varsmbUrl="smb://" + DOMAIN + SMBROOT

        // getViewModel for SmbConnection
        valsmbViewModelFactory=SmbViewModelFactory(USER, PASSWORD, DOMAIN, smbUrl)
        valuembViewModel:SmbViewModel=ViewModelProvider(this,smbViewModelFactory).get(SmbViewModel::class.java)

        // connect SMB server
        if(!smbViewModel.connectSmb2(){
            finishAndRemoveTask()
        }

        /*
         * get data in SMB server
         */
        // Create the observer which updates the UI.
        val pathObserver=Observer<String>{sPath->
            binding.tvSmbPath.text=sPath
        }
        valueObserver=Observer<Long>{sSize->
            binding.tvSmbSize.text=sSize.toString()
        }

        smbViewModel.smbPath.observe (this, pathObserver)
        smbViewModel.smbSize.observe(this,sizeObserver)
    }
}

import androidx.lifecycle.LiveData
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import jcifs.CIFSContext
import jcifs.config.PropertyConfiguration
import jcifs.context.BaseContext
import jcifs.smb.NtlmPasswordAuthentication
import jcifs.smb.SmbFile
import kotlinx.coroutines.*
import java.util.*

class SmbViewModel (val user: String, val password: String, val domain: String, val smbUrl: String): ViewModel() {

    // Configure LiveData
    private val_smbPath:MutableLiveData<String>by lazy{
        MutableLiveData<String>()
    }
    valuembPath —LiveData<String>
        get() =_smbPath

    private val_smbSize:MutableLiveData<Long>by lazy{
        MutableLiveData<Long>()
    }
    valuembSize —LiveData<Long>
        get() =_smbSize

    /*
     * Connecting to SMB Server
     */

    // Connectivity to SMB Server Example 1
    funconnectSmb1(): Boolean {
        varretBool: Boolean=false

        viewModelScope.launch (Dispatchers.IO) {
            val prop=Properties()//java.util.Properties
            prop.setProperty("jcifs.smb.client.minVersion", "SMB202")
            prop.setProperty("jcifs.smb.client.maxVersion", "SMB300")
            valbc = BaseContext (PropertyConfiguration(prop))
            valcreds=NtlmPasswordAuthentication(bc,domain,user,password)
            val auth —CIFSContext=bc. with Credentials (creds)
            val smb = SmbFile(smbUrl, auth)
            if(smb.exists()){
                // Set data from SMB server in LiveData
                _smbPath.postValue(smb.path)
                _smbSize.postValue(smb.length())
                retBool=true
            }
        }
        Thread.sleep(5000)
        returnBool
    }


    // Connectivity to SMB Server Example 2
    funconnectSmb2(): Boolean {
        varretBool: Boolean=false

        viewModelScope.launch {
            valueAsync = async (Dispatchers.IO) {
                val prop=Properties()//java.util.Properties
                prop.setProperty("jcifs.smb.client.minVersion", "SMB202")
                prop.setProperty("jcifs.smb.client.maxVersion", "SMB300")
                valbc = BaseContext (PropertyConfiguration(prop))
                valcreds=NtlmPasswordAuthentication(bc,domain,user,password)
                val auth —CIFSContext=bc. with Credentials (creds)
                val smb = SmbFile(smbUrl, auth)
                if(smb.exists()){
                    // Set data from SMB server in LiveData
                    _smbPath.postValue(smb.path)
                    _smbSize.postValue(smb.length())
                    true
                } else{
                    false
                }
            }
            retBool=retAsync.await()
        }
        returnBool
    }

    override fun onCleared() {
        super.onCleared()
        viewModelScope.cancel()
    }
}

import androidx.lifecycle.ViewModel
import androidx.lifecycle.ViewModelProvider

classSmbViewModelFactory(valuser:String, val password:String, valdomain:String, val smbUrl:String):ViewModelProvider.Factory {
    override fun<T:ViewModel>create(modelClass:Class<T>):T{
        return SmbViewModel(user, password, domain, smbUrl) as T
    }
}