This is a polite and gentle way to remind someone of something they were supposed to do. (To "remind" someone means to say something to help them remember.)
"I wanted to (do something)" is a polite way to start any question when you need to ask but you don't feel that confident about it.
For example, if you want to invite someone to hang out with you, you can call them and after a few sentences of small talk you can say:
I just wanted to see if you're free on Thursday night. I'm going to this art show with a few friends of mine.
People use "I wanted to remind you that..." in business situations pretty often. It's more common in spoken English than in writing.