Okay to remove light switch and cap wires?
There is nothing unsafe but may be a local fire code issue. I recently checked on my areas local code as I was asked to remove 4 bedroom switches and a living room area, similar to what you want.

The person I talked to said if the remote is not over the switch they can toggle the switch for a couple seconds and the lights respond. Although it is not a law yet the person I talked to said they are trying to get the required switch mandated to be hardwired and the “legal issue” will be based on the date the house was built. 
Low voltage remote switches will be allowed as long as hardwired.

There justification is the person in need of care had the remote and first responders could not activate the lights. She said responders getting injured on several occasions and the possibility that some patients have died because of delays due to darkness and tripping in the dark while responding. 

She said today a switch is not fully defined for safety reasons and they are working on making hardwired a law. But at this time they recommend the type that located the new remote over the switch in the on position that if the remote is out the switch handle can be toggled. 

After talking to the owner they decided to not remove the switches, however today it would not be in violation of former or electrical code.