You can add/remove/update lock codes using the ST CLI. Using “smartthings devices:commands” and selecting your lock device, you have the following command options:
Commands:
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1 setCodeLength(length<integer>)
2 reloadAllCodes()
3 unlock()
4 unlockWithTimeout()
5 setCode(codeSlot<integer>, codePIN<string>, codeName<string>)
6 requestCode(codeSlot<integer>)
7 lock()
8 updateCodes(codes<JsonObject>)
9 deleteCode(codeSlot<integer>)
10 nameSlot(codeSlot<integer>, codeName<string>)
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There is also the option to use the 3rd party Seam application to manage lock codes.