Deleting InfluxDB points with no tag - influxdb

Question

I have a few points that I am trying to remove that came from bad data and keep reading that you can't really do it but find it hard to believe you really can't.
They have no tags so I tried to give them tags by overwriting them with a tag, then deleting the tag, but it didn't overwrite and i just deleted the new tagged values.
I have the time so tried to delete with where time = 'x' but get a 400 from Chronograf, tried again in Influx CLI with DELETE FROM "apps" where time = '2019-05-01T17:45:00Z' and it runs with no errors, but doesn't actually delete the point.
I understand that because of the way Influx indexes things you can't delete based on fields, but there has to be a way?
Thanks.

Answer 1

I haven't seen explicit examples on deleting series with no tags in official Influxdata docs. But approach like in example below worked for me in test - it drops all series in measurement demo with empty tags. Be careful to include all possible measurement tag names in where clause or you risk to drop good data too.
> drop measurement demo
> select * from demo
> insert demo,tagA=A,tagB=B value=5 123455
> insert demo,tagA=A value=6 123456
> insert demo value=1 123451
> insert demo value=2 123452
> insert demo value=3 123453
> select * from demo
name: demo
time tagA tagB value
---- ---- ---- -----
123451 1
123452 2
123453 3
123455 A B 5
123456 A 6
> drop series from demo where tagA='' and tagB=''
> select * from demo
name: demo
time tagA tagB value
---- ---- ---- -----
123455 A B 5
123456 A 6