How to remove ‘Excerpt’ ; ‘Custom Fields’ ; and ‘Post Thumbnail’

Hi all,

I have an open blog https://www.whatshappeningprovo.com. I’d like to simplify and decrease the chances of someone getting confused when making a post on the site.

I don’t feel like the ‘Excerpt’ ; ‘Custom Fields’; and ‘Post Thumbnail’ functions are really needed for my purposes as of right now.

Is there anyway to turn these off in order to not confuse people that may be learning how to post something on the site for the first time?

Thanks all.