How do I delete the real estate part of the total net worth ?
Hmm, exactly what do you mean?
If you don't want to count the real estate in your net worth, you could delete that asset account or accounts or you could just zero out those accounts.
If you mean, how do you get Simplifi not to list Real Estate section under Assets in the Accounts Bar (on the left), you cannot.
There are some ideas for rearranging the Accounts in the Account Bar and/or hiding them. There's also another for not showing the Net Worth on the Dashboard Page. Here's one idea. You can upvote it if you think it fits your needs.