I have a intertherm air handler electric heater that is not working properly. I turn the thermostat on off and it all shuts off but the heat strip are still on or I guess the heat is still,on.

I moved your question to HVAC forum, so our professionals can help.

Could be the heat strip is still hot and needs to cool down, or, if this heater truly stays on with the stat off, then could be a stuck relay.

FYI, working on an electric furnace is not a DIY project, should call in a qualified tech.