Deleting E Mails

I am running Mountain Lion and I have something like 13,00 0 emails in my in folder and I am not able to delet them. I have selected and then delete but they come right back. I have moved them to the trash and again they come back. I have done everything I can think of but nothing seems to work. Do you have any idea why I am not able to get rid of them?
Any advise would be greatly appreciated. thank you very much.
TheCajun

How is the account set up against your e-mail provider? If it's IMAP, then changes locally should be reflected on the server and deleted email should disappear. If POP, then you are downloading a copy of the e-mail and unless you specifically tell the client delete mail from the server, it will keep coming back..

It is set as IMAP. When I checked preferences/ accounts it shows iCloud IMAP and GMail IMAP. When I delete the Email it appears to be deleted but in a few moments they all come back. I am sure it is something simple that I am overlooking but not sure what it is.
TheCajun