Click View>Layout>Message List Header

If you mean the other quick filter, just rightclick mouse on the bar and drag the quickfilter off.

thank you it worked. I appreciate it

also will there be more add on/extentions added i have a few that i had that are not listed yet

The answer to that question depends on the authors of the add-ons. If they choose to work up new versions of their add-ons, you'll find them listed as compatible with 115+. The developers of Thunderbird have no control over the authors, who may or may not decide to persevere with creating new versions of add-ons.