Why does my bathroom shower have too much water pressure?
The simplest way to reduce pressure would be to use the water turn off valves usually located in the wall or under the floor near the shower controls. Turn both  the hot and cold shut offs back to apx half or simply turn on your shower as you would normally use it, then adjust the valves until you have a flow and pressure you like. Playing around with the hot and cold will effect the temp of the water related to your shower control settings. You may have to experiment a bit, but you can control both the max pressure and temp this way.

The other way to adjust pressure and temp on a one handle shower control is sometimes done inside the valve body. For this adjustment, you should have the installers manual. It will show you how to adjust the position of limit disks inside the valve body. These are common on newer scald resistant shower units.