you mean remove leading zeros or zeros in the least significant digits after the decimal in a string format? or just test for zero and change it to a blank?
for your simplistic case, the simplest thing is:
TextBox = iif(TestVar = 0, "", TestVar)
you can get more elaborate using iif(), Replace(), Format(), CStr(), CInt()/CSng()/CDbl() and I'm sure there's many more functions that you can throw together to do whatever you'd like.