Was it named by touching the device or in the device record? If you named it on the device and you have a naming policy then that will take precedence over the manually typed name. If the device record already has the asset tag in it why not just have a policy to use it as the name versus touching the glass?
Either under Automated Device Enrollment or it came from a placeholder. In most cases if one exists it will be tied to an ADE profile. To verify one exists goto a device record and look under the name to see if a policy is in effect like in the example below:
If that's the case start with your ADE profile.