Windows 7: Cannot access file due to permissions

Dell Desktop Windows XP 32 bit IE7 no free memory to download anything. Can't remove programs, no security tab. No windows installer in safe mode. I've confused myself now. Cannot access any file due to permissions. Need to know how to remove programs, then reset permissions. I've been trying to work on this for two days. Can't seem to make sense of any of the great information and tools available, because I don't know which to address first.

I would first run some virus and malware scans. Then use command prompt to delete everything you don't want. As for malware software use something like malwarebytes, super anitisoyware, along with spybot search and destroy