Deleting markers into project song

[Guest]

Hello guys,
i have a small problem with a project song, so i used one of the templates which had many markers on it and when i attached my midi stuff the markers count become huge and it slowed the computer, i tried to delete them, but didn't succeed i started deleting them one by one and it was very slow, then i marked them all and pressed delete, waited for one night and NOTHING happened, the program didn't respond...
so can somebody tell me a EASY way to get rid of them?