./wlst.sh
You will get WLST prompt in offline mode, invoke the following command

wls:/offline> domain = "/opt/apps/user_projects/domains/domain_name"
Note: change the domain path if necessary

wls:/offline> service = weblogic.security.internal.SerializedSystemIni.getEncryptionService(domain)
wls:/offline> encryption = weblogic.security.internal.encryption.ClearOrEncryptedService(service)
wls:/offline> print encryption.decrypt("{AES}WDhZb5/IP95P4eM8jwYITiZs01kawSeliV59aFog1jE=")
weblogic123
wls:/offline>