Should I lower or rappel from the anchor?
Lowering a climber will very slightly wear a fixed steel anchor due to the running friction of a weighted rope on the metal surface. This is especially true if the rope is dirty and has lots of grit in it. Over time, as many people lower on the climbing hardware, the bolt hangar or ring will need to be replaced.
For this reason, it's sometimes suggested that climbers rappel instead of being lowered off their climbs.
However, if you're new (or even relatively new) to climbing outdoors, it's always okay to lower off fixed anchors if it feels safer or easier. If that increases the wear on the steel hardware, so be it. We don't know anyone — route developers or otherwise — who wouldn't happily subsidize the cost for hardware replacement if it keeps more people safe.
Whether you do end up lowering or rappelling, make sure your decision is clear to your belayer before leaving the ground. There are far too many accidents that occur due to misunderstanding.
If you feel guilty about lowering off climbs, please contribute to hardware replacement by donating to the American Safe Climbing Association (ASCA).