lightning input field lwc - How can I make it not required?

You are confusing lightning-input with lightning-input-field. lightning-input-field lwc will follow the field's configuration (required or not based on how it was created under setup > object > field(s)) and is dependent of the record-edit-form. It uses the record-ui API to determine a number of things, including if it is required or not. vs lightning-input which does not, as it is "standalone" If you want to make it "not required" you will ahve to modify the field settings directly, vs adding a required attribute if you were using a lightning-input field