Not Clearing previous group

I have made this dinamic form when you pick a reagion shows a community, when you pick a community it loads the centers on that community. The first group that loads the region also loads the type of centers, then depending on the community you pick it shows the centers and type of centers, and if there are no centers on that community it should not show the type of centers. But 2 things are happening. 1 the types of centers of group one are not clearing when picking something else. 2 If I put all the 480 communities, then the form stops working. Please help.

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