If you want to delete Facebook then delete it. If you’re not sure then deactivate it for a month and see how you feel about it. Then after a month, if you still feel the same, delete it. Don’t look back. There’s no need to announce on Facebook your intention to leave Facebook. There’s no need to overthink any of this. Just delete it and have done with it. I deleted my personal account outright and it was about two or three years before I returned. Now I have a couple of locked down accounts for Facebook groups and to help promote my work. But most of my Facebook friends never came back. I’ve no desire to be on Facebook — its use is solely utilitarian as a way to promote my writing. Facebook is a trash fire and the world would be better without it.