To change the current directory in a VBScript
to be the folder that the script is started from:

set oShell = createobject("wscript.shell")
oShell.currentdirectory = wscript.scriptfullname & "\.."

To prove that this works, try:

set oShell = createobject("wscript.shell")
wscript.echo oShell.currentdirectory
oShell.currentdirectory = wscript.scriptfullname & "\.."
wscript.echo oShell.currentdirectory