I just tested this on 8.0.9:
Tag configured with no overrides:
def callback(result):
print result
system.tag.writeAsync(['[default]DPB/PI05051/CMD/OVR.Enabled'],[False],callback)
After running that script, Enabled override is on and it is set false:
The override was set automatically with the tag write.
Are you on a different version, or is there something different in what you’re trying than in the test above?