Pay off my unsubsidized loan while in school?

I'm an undergrad junior and my first year of college I took out a small unsubsidized loan of about $2000. So far it has accrued an interest of about $300. I have extra money left over from grants, scholarships, work, and subsidized loans that I won't need next school year. Also, I already know that I won't need to take out another unsub loan. Could I use the extra money to pay off my unsub loan, or is that against the rules since I would indirectly be paying off an unsub loan with a sub loan? Hope that makes sense, thanks.