Replacing the blower motor?

Just to be sure, you are talking about one of the 3 screws that holds it in place that is shown in the process below?

If that is the case, then you will need to try and extract it but just be careful when you are trying to drill this as it is in plastic.

https://www.youtube.com/watch?v=YDt5OUIZTs0

If you have any threads sticking out of the hole then you can use vice grips to grab it and twist it out. However, you are going to want to do this with the blower out so that you can try and have better access to the screw.

Lastly, if I am missing the issue can you get a picture of what it looks like and we will be able to figure out how to get it out.