Seems a lot of new phones are coming out with non removable batteries. So what do you do when the phone hangs & does not respond. On the rare occasion it happens with my old phone one can simply remove the battery.

There should be some button combination which you can press and hold which accomplishes the same thing. 

 

What is the make/model?

 

Often it is: hold volume down and/or up and simultaneously hold the power button for 5 - 10 seconds.

On my Samsung you push the home button and the one that you use to shutdown the phone at the same time if it locks up.

Thx for the help. Not sure what phone yet as just looking to buy but your info leaves the choices wide open

Holding down the power button for several seconds should hard reset it.   Maybe in combination with holding down the volume up or down but not sure.

Less of a problem with newer phones. Things have improved a lot.