How do I delete/unload old flight plans?

Have read threads on here about deleting and unloading old flight plans.
Yes I’m a new user (and old) but getting frustrated shurely a simple delete button would be a simple thing to do? Can’t see a unload button either.

Can I build a flight plan from the Navigraph icon in msfs 2020? Or should I do that outside of msfs?

So far when I create a plan cannot get the aircraft to follow it. (Fenix A320) tried following steps found on here to load into MCDU but does not seem to work. (cannot complete all the steps)

Thanks