ttps://{{dnac}}:{{port}}/api/v1/tag/association/{{tagId}}?resourceType=network-device&resourceId={{deviceId}}

DELETE https://{{dnac}}:{{port}}/api/v1/tag/association/{{tagId}}?resourceType=network-device&resourceId={{deviceId}}

Deletes association between tag and device

you need to delete the association before you can delete the tag