I have had my trek roscoe 8 for a year now, and the tires are becoming worn out. The tires are tubeless bontrager 29x2.6 xr4 and they are a bit overkill for what I need. Would it be a good idea to a 2.5 or a 2.4 because most of the riding I do is on the street? Would it be a good idea to go back to tubes for the easier maintenance?
Swap tires to suit your needs and enjoy the ride. Tubes vs tubeless - not sure what "easier maintenance" you mean with tubes. I find tubeless to require less maintenance since I don't get flats as much as I did when I was running tubes. But if you had a different experience then that's fine - just put tubes in and get rolling how you like.
You can go with even smaller than 2.4 if you're riding only street. If you want to stick with bontrager, XR2 or XR3 are good options.
I swap tires on my Roscoe depending on the conditions and find tubeless too messy. Also, depending on how many bikes you have, topping up the sealant on a bike I don't use regularly for months at times seems like a waste. I run XR2 rear and XR4 front in the dry, and use lightweight tubes (pirelli scorpion smartube). I guess it would depend on where you ride, but thankfully flats aren't an issue for me with the wide rims and big volume tires.