The Clear variable removes the value from any existing variable. It does not remove the variable itself. For example, the following example calls Write-Host twice: on the first occasion, it writes the variable value; on the second occasion, it does not write anything:

PS> $temporaryValue = "Some-Value"
PS> Write-Host $temporaryValue -ForegroundColor Green

Some-Value

PS> Clear-Variable temporaryValue
PS> Write-Host $temporaryValue -ForegroundColor Green