Hi, I have two citrus trees at the house I just bought. They are yellow mostly but seem to turn orange after a while. They are really sour and have thick lumpy skin.

I'm not sure if they are a type of orange or if they have a disease? Is there anything to do to make them sweet, or do I just chop them down. The trees are huge and give good privacy but I'd rather have something that produces good fruit. Does anyone know what they are and do they have a good use or can I 'fix' them? Thanks!