This type of question pops up on a regular basis - how can I update SAS metadata using SAS code? My usual response is yes you can but if this is just a one-off change then you can do it far quicker manually and not have the danger of corrupting your metadata repository as well.
If you have a lot of spare time to understand the SAS metadata model, and to build and test some pretty complicated SAS code, plus be OK with corrupting your metadata repository while getting your code right, then here is a good place to start your journey:
https://documentation.sas.com/?docsetId=lrmeta&docsetTarget=lrmetawhatsnew94.htm&docsetVersion=9.4&l...
And this library article too: https://communities.sas.com/t5/SAS-Communities-Library/Examples-DATA-Step-Functions-for-Reading-Meta...