In turn your tenants expect you to honor their one year lease (or whatever the duration).Put yourself in their shoes, how would you feel if 6 months into your lease the landlord was trying to get you to leave because it was more convenient for the landlord and his financial goals? 

If I am in your shoes I go through with the sale and start my BRRRR journey with the next property.

I was in your shoes 6 months ago.

I'd hop on google in your shoes.

Just a thought if I were in your shoes 

Point is, I wouldn't pay off the student loan if I we're in your shoes. 20K can go so much farther in real estate, assuming you know what you're doing. 

If I'm in your shoes I would drop price to sell it even if it means lose some money on this deal.

If I were in your shoes I'd want a lump sum payment several years down the road with no prepayment penalty.  

Walk in the shoes of the target market.

Fix and flipping and wholesaling are really no different than a shoe store or a widget factory.