Sell now or keep renting it out?

[Eduardo Fumo]

Hey guys, 

I am new to all this and my dad asked me to give him my opinion on what to do with his rental property that he bought in cash 7 years ago for $165,000. So I am going to ask the experts.....you guys!!

It's a 3bed/2b 1600sqft super nice neighborhood. He is charging $1800 rent which he pockets all of it since he manages it and owns it.

Zillow says its estimate value is $261,000 but I am sure it's worth more. 

Question is should he sell and purchase another rental or two? or continue to pocket the rent.