Ok. There's a much easier way to this than setting all to "No" and 0 as
@Brogan earlier mentioned.
ACP -> Groups & permissions -> Permissions -> User permissions and select the user.
Use the top-right menu (assuming XF 2.1), choose this and save.
View attachment 215828
They are all now "No" and 0; even the add ons. And, they'll be removed from the user permissions list.
But, I don't know if we're talking groups or user-specific permissions as I previously asked this question before about groups and got the same answer to clone from a demo setup, which I had to do because I messed up one group (there should be a reset to original option, but... whatever, my mistake).
If we're talking groups, you're definitely going to have to make a demo of some sort and copy the options over (let's say you let Registered see IP addresses, you can't just reset it, you need to go in and change each value back to its original installation state, which can only be done by the demo install).