Need macro to remove item and reset back to zero

I need help creating a macro that will remove a stock item from one tab and reset to zero so the macro can be run multiple times. The crux I am facing is being able to use this as a counter but in a negative sense. On the 'PRODUCTION'tab, I need to have the capability of removing stock item "TANK SIDE" from 'DS TANK' tab when a serial number is entered on the 'PRODUCTION' tab. The 'DS TANK' and 'PS TANK' tabs our inventory tabs and need the ability to add and subtract parts as they are produced and taken for assembly. I have attached a file for your perusal.

WORKSHEET 03-26-2015.xlsm40.19 KB