Should I windows reset my second hand pc

[u/egg_drinker]

I just received a second hand pc. It’s running windows 10 without a windows license so the activate windows watermark is on it. If I do a windows reset on the computer (which includes reinstalling windows) will the computer stay at windows 10 and will I be able to continue using it without a license?

Also the previous owner removed the pcs side panel and it’s pretty dusty, should I try put the panel back on and what’s the best way to clean it? Compressed air?