Add 'clear' button to adjustable keypad please

I have been working on a customers test rig that tests different components at various pressures.

When carrying out extensive testing of various components it has become quite frustrating to adjust the pressure test value on a constant basis. I have inserted a parameter that allows the customer to adjust using the built in keypad, and although I can make a button to raise and lower this parameter on screen, this too can be annoying as the range of pressure values is quite large. They need a 1psi resolution and it can be between 0 and 15000 psi.

The easiest solution was to insert the parameter as an adjustable and use the built in keypad as shown, but I have found its quite laborious to press the delete button for each digit on screen before entering in a new one, and with it being an MD4 its not as responsive touch as the new MD5, sometimes missing button presses. If I'm going from 15000 psi to 3000 psi, it involves deleting the whole existing number manually digit by digit before entering in the complete new number. Without any way of just removing the 15 and replacing it with a 3, can there be a delete button (or cross for example) to 'clear' the whole number instead of just a digit by digit delete as illustrated below rather than just the single delete button? 

 The current keypad with single digit delete button:

The ideal setup with modified keypad:

There may be an easier way around this issue that I'm not aware of!