BASIS FOR YOUR AS-REPAIRED VALUE (ARV): When you flip a house, it’s important that you know what you are going to sell the property for.

Reach out with what you are trying to sell and I will see if I can help you find a buyer?

If it does, the interest rate doesn't matter as it is just a part of the calculation.You might also look at selling one or both of the properties in a 1031 exchange and buying into a new property (or several) that provides higher returns. 

Depreciation in price only really hurts you if you HAVE to sell.

BRRR or sell is the only way to do it.

When reviewing the cash flow of properties, you discovered the cash flow was not feasible for a property, you could consider a 1031 Exchange to sell the property and replace it with a new property in the most tax efficient manner.Review profit margins and cash flow for each of your properties.Is the cash flow of each property still as projected when you purchased the property?

We will be selling the house

He also wanted to cash out on several of his investments and fully "retire", hence reason for selling.

I stumbled into my 1st deal when my parents' neighbors decided to move and preferred to sell off market.

They will try to sell you hard though.