Hi Matt,
You can remove all the selected options by clicking the ESC button once if the popup is closed and twice if the popup is open. I'm marking this feature request as declined because this is the button that allows the user to clear the input through the keyboard.
You can try the above action in the following demo:
https://demos.telerik.com/blazor-ui/multiselect/keyboard-navigation
I hope this helps. Please let me know if you need any further information. Thank you.
Regards,
Hristian Stefanov
Progress Telerik
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