Uninstalled Dell Data Proection software which has caused problems

Recently I bought a desktop PC from Dell. I kept getting reminders about completing the set up of the Dell Data Protection software. Once I did this I was not happy that it kept asking if I wanted to encrypt each item, so I decided to uninstall the program.

When I did remove it I found I had limited access to my files. If I opened a word document I would get the message "Word cannot open the document: user does not have access privileges." If I opened an Excel document I got the message "Excel cannot open the file because the file format or file extension is not valid. Verify the file has not been corrupted and that the file extension matches the format of the file." When I open a picture I get the message" It appears that you don't have permission to view this file. Check the permissions and try again."
Finally if I try open the iTunes library I get the message " The iTunes .itl file is locked, on a locked disk or you do not have write permission for this file."

Any ideas please on how to get back unimpeded access to my files?