You can limit the % processor time, # of processors, % of memory in My Grid --> Device Manager --> Device Profiles --> Default. You can also restrict it to only run when the computer is not in use (e.g. as a screensaver) and/or to specific days/times. You can do the same settings in the client: Advanced view --> Advanced --> Preferences (note the client preferences override website preferences).

Finally, if you are still unsatisfied with any of these options, you should be able to remove the program. If using Windows: Control Panel --> Add/Remove Programs.