Try using Revo to do a clean uninstall.
http://www.revouninstaller.com/start_freeware_download.html

You need to put the Terminal Server in a special installation mode before you install any program.

Option A:
If you go in the Control Panel, choose Install Application on Terminal Server tool under Programs. Proceed with the install as you normally would.

Option B:
Open up the command prompt and type "change user /install" (w/o quotes). This puts the TS in installation mode. Install AC. Then once you are done. DO NOT forget to put the TS in back in execution mode by typing "change user /execute" in the command prompt. Note: Option A changes the modes automatically.