can you use gear removal on porobot?

Yes. Patched Porobot is both a Unit and a Gear, so effects that remove gear — like "Kill a gear" or "Banish a gear" — can legally target it.

Rule 178.3 says a Game Object with multiple types can be affected by effects that interact with any of its types, and the rules give this exact example: "A unit that is also a gear can be targeted by spells and abilities that say 'Kill a unit,' or 'Kill a gear.'" So gear removal works on Porobot just like it would on any other gear — it goes to the trash (or banishment) like normal. (It keeps its unit properties too, so it still enters exhausted, has Might, and isn't recalled to base during cleanup.)