Deleting facet won't delete its values

[chladog]

Describe the bug
The facet values are still present in Facet selection input when creating/editing product after deleting their "holder" facet.
There is no tool to remove them manually after holder facet is gone.

To Reproduce
Steps to reproduce the behavior:

1. Create facet "x"
2. Create value "y" of facet "x"
3. Delete facet "x
4. Create new product
5. Facet value "y" of "x" is still present in "Add facets" option

Expected behavior
When I delete "x" I expect not to see "y" and any other values of "x" in the system anymore.