I just want to know how to remove campaigns in Adwords that are not running. All my deleted campaigns still show 'deleted'. I want to remove them but unable to.
I think that's just the way it is. In any case you shouldn't remove them. You may want to look into them later to see how you could improve future campaigns, which keywords worked, didn't work etc.
One of the rules of database design is to never physically delete anything. You mark it as deleted but it should still remain in the database. The reason is to keep historical data as well as not creating orphaned records when it's linked to other data. In Adwords, there is the option to "show all but deleted" at the campaign, group, ad and keyword levels. It's the very first option under the tab menus.
I would take a copy of them and save it elsewhere and then delete them from Adwords, whether you still can see them or not. Because they are well known for suspending Advetisers that are saving old ads put on pause, because they suddenly do not comply with their terms and conditions anymore. Adwords do not separate ads that are paused with ads that are running when it comes to terms and conditions. And even if their support can see you are right, there are no mercy, you keep being suspended.