Computer BIOS following the UEFI specification as defined should have several keys. There should be a Platform Key (PK), a Key Exchange Key (KEK) as well as a key database and a forbidden signatures index.
No-no deleting KEK
You should NOT delete the Key Exchange Key (KEK) unless you know your system if compromised or you have another good reason to do so. You really do need it both for proprietary operating systems like Windows and free software operating systems with support for UEFI keys.
While it may seem like a joke and you don't like KEK for some reason - don't just delete important BIOS keys for no good reason. Your computer will stop working if you have a proprietary operating system installed.