Actually, you cannot overwrite or delete the factory programs and presets on the H90.
To scroll through the default factory list – on the pedal itself press the Programs button, and with Quick Knob 1 select the Factory 1 list. You can then use the Select knob to scroll through the list.
If I remember correctly, the Factory 1 list is also loaded as a user list by default when you first use the pedal. this list is editable and I’m guessing these are the presets you overwritten.
Also, keep in mind that the Factory 1 list does not contain all of the factory programs, it’s a collection of 99 selected programs. To find more factory programs you can view the different lists on the pedal, or choose ‘All’ to see all of the programs the pedal holds (including user programs).
All of the information that udi9 has said is correct.
You could export your current list with the Programs you made to save a copy of them, and then factory reset your pedal to get the User 1 list back to the default state. Then import your custom Program list.