Can a base salary be lowered by a company for a Sales Person by simply changing their title?

Do you have a contract which specifies how much you must be paid and for how long you must be employed, or otherwise limiting your employer's right to fire you?  Do you believe that your pay was cut for some reason prohibited by statute (e.g. race, gender, religion, etc.?)  If not, you have no guarantees that the terms of your employment will remain the same.  Your employer is essentially telling you that it is no longer willing to pay you the same compensation, which, assuming your answer to the above questions was no, it has every right to do.  You have the choice of whether to accept the new compensation your employer is offering or quitting.