@Cheryl608
Depending on the host refund policy, you do not need his approval. The earlier you cancel, the better - hopefully you will have no issues.
Go to MY TRIPS, click on Change or cancel, and click on cancel.
This should tell you if you have any penalty.
If so, call airbnb and they can cancel it for you, so you have time to get your refund and book somewhere else.
Here you have telephone numbers
https://community.withairbnb.com/t5/Help/Contact-Airbnb-A-Community-Help-Guide-UPDATED/td-p/413245