Categories that are not currently needed can be hidden by using the down arrow by each category name. An example is budgeting savings for a large cost (e.g. washing machine). After the purchase is made, the category can be hidden.

I would love to take Actual, if somebody was going to do this, is to focus less on the zero-based budgeting - and if any Actual users are listening to this, don't freak out; that's always going to be there. But there's totally a capability for this to be a more generic transaction management tool