That's not gonna work as that means having to dish out more moneys...
1. What is the FULL TITLE of the version you purchased. For example, I have "The Sims: Complete Collection".
2. Where did you buy it from
3. Your description of the problem is vague. Either way, if for some reason it came "modded" (which they don't, unless you downloaded it illegally in which case your aversion to spending monies on the product in many ways is the cause of the problem to begin with) there is no way to "unmod" it.