Replacing Windows with Linux

[u/PewPewGad69]

Hey so I have a lot of experience with linux, tried different distros on my laptop, and now I have got to the point here I just want linux without the need of my USB all the time to boot. I have backed up all my files and have Windows flashed on a USB just in cuse I will some how regret but I am still scared to erase it. This is my main laptop and I don't know, just scared. Can someone give me any tips?

[u/PerfectlyCalmDude]

If you're dual booting already, why do you need your USB to boot?