Anyone know if its possible to null the value of a field in a workflow? We're getting the following pop up Warning: this copied transaction uses the following inactive classes. You should remove these classes before saving if you do not want their balances to changes".

Yes, you use the Action Set Field Value then choose "STATIC VALUE" and leave it empty

thanks! it looks like it does blank it out, but the pop up warning still occurs

Not sure to be honest, maybe change the Workflow "TRIGGER ON" setting, and use Before Record Load The TRIGGER ON can be set at Workflow or at Action level.