Can I remove the 3 dots on the top while still keeping multitask on my iPad?

The three dots “button” that will be seen at top-centre of App windows is a fundamental element of the iPadOS User Interface - intended to simplify use of full/split/slide-over multitasking and Stage Manager. This control cannot be hidden or suppressed - and neither can multi-tasking be disabled in iPadOS15/16.

Information about using multi-tasking can be found in this support page:

Use multitasking on your iPad - Apple Support

The iPad User Guide is also a rich source of information about using iPad and its many features. The Guide is available both online using a web browser (such as Safari), or as an Apple Books download:

iPad User Guide - Apple Support

https://books.apple.com/book/id1567104892

Apple do invite constructive feedback, comments and feature requests via their product feedback pages. For iPad and iPadOS:

Feedback - iPad - Apple

No.

The multitasking dots are an integrated part of the iPadOS UI.