I'm thinking of deleting most of the posts I make
Why do you want to delete most of your posts?
I think I made some silly posts in the past.
People make a lot of posts they may come to regret. Next time think before you post so you can put things up you are proud of.
I don't know how to delete them can you help?
It is good to remove things after you feel they might be bad. You can go to the setting normally and they will have options for history and you should be able to delete posts you have made from there.