You can terminate x by calling a run-level that does not use it.
Open a terminal and us su to become a root user.
Enter 'init 3' without the quotes.
You will see the runlevel you are in shut-down and the new one will start up.
No x means no gui so be prepared to work in text mode.
You will have to sign in as user first. Then just type 'vasm' again without the quotes. Then choose super from the list. This should get you back to the choices you had when using VasmCC
What program are you trying to run.?
Here is a little more on init and runlevels...http://www.opensourcebistro.com/Tutorial/VL60/terminal/init/run-levels.htm