How To Remove The Poll Tab From Your Facebook Page September 24, 2020
Jan. 26, 2021 update: Facebook has just announced a new experience for Business Pages that should be available in the upcoming months. If you are not able to remove the tab from your Page using the procedure below, please be patient. The new page experience will fix the issue.
Facebook is buggy and incomplete when it comes to managing Page tabs and the only workaround to remove a tab is to use the old Facebook interface. To switch to the old interface, open your Facebook page in a browser and replace the subdomain in the address bar from www to business. The new URL should look something like https://business.facebook.com/mypage where "mypage" is your page username.
Now that you are using the old Facebook interface, click the Settings link on the top right of the page.
From the Settings Page, click the Template and Tabs menu on the left hand side of the page.
You should see the list of tabs installed on your Page. Find Poll in the list and click the Settings button next to it.
A list of options related to the tab will appear. Toggle the on/off switch to hide the poll tab and click the Save button.
Now when you navigate to your Page, the tab will no longer appear.