If I'm understanding correctly, you want to remove all contacts from a list while keeping the list itself. If that's the case, you could click on the list name you want to clear so that it opens up and you see all contacts within the list. You can check the checkbox at the very top (in the header area) to select all contacts within the list. From there you can choose "Remove from list" - This will clear all contacts from the list, but the list name will still exist with 0 contacts until more are added.
Let me know if I misunderstood and you're looking to do something different!
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