How do I get rid of ionizer ozone?
I just read that air purifiers with ionizer can create ozone. Which can cause serious health issues like chest pain and other issues. I just turned mine off and don’t plan on using it anymore. Does ozone stay in the air even with it off? If so how long? Also will I need to take some other measure to get the ozone out the air?

It depends on the temperature, humidity, and how many consumables are in the room.
A standard room ionizer, is usually non-detect within 10 feet, so it’ll decay entirely back to oxygen throughout the room in a matter of 15-30 minutes.
Larger "remediation" type units might last up to two hours.
Increasing temperature and/or humidity, adding visible light, shortens the lifetime of the ozone.
No other measures required.