To access the Strip Poll from Topic panel, click the following: Threads & Posts > Strip Poll.
If you wish to remove a poll from a thread, you would click on the Strip Poll option and you will be presented with a simple form:
To remove the poll from a thread, you simply need to enter the thread ID that the poll is contained in. To obtain the thread ID, find the thread you want to remove the poll from. The link to the thread should look like https://www.example.com/forum_title/x-thread_title where forum_title is the forum title, thread_title is the thread title, and x is the thread id you want. You would enter x into the form on this page.
Once you have found this, submit the form. You will receive a screen where you can confirm that this is the correct poll. Simply submit that to remove the poll.