It's fine to leave them. The people who create these forum profile links will be doing it manually. Whether they're nofollow or dofollow, people will still try

It's fine to leave them. The people who create these forum profile links will be doing it manually. Whether they're nofollow or dofollow, people will still try to build these links. Nofollow is another thing that isn't important as used to be. Sure dofollow does give you more link juice, but nofollows are still good. If you have 99% dofollow links to your site it's going to look unnatural, so a good mix of dofollow and nofollow always heps.