[heinrichhartman]

Since they have not yet extended an offer to you, it would be foolish to drop out of any other interview processes you are currently involved in.

And even when you have the offer on the table, since you already started the process, I would probably follow through with them in any case.

You are in a much better position if you have competing offers. This is what allows you to negotiate, and leave the company quickly if you don't like it.