Delete Multiple Sheets in Numbers

you cannot. You have to do it one at a time.

you can post feedback to Apple using the Numbers menu item "Numbers > Provide Numbers Feedback"

if you want to keep all but one, you can select the one you want, then copy using the contextual menu for that sheet, then create a new document and paste the sheet you copied.

Easily done with a short script.

1. Copy-paste into Script Editor (in Applications > Utilities)
2. Make sure Script Editor and Numbers are listed and checked at Security & Privacy > Privacy > Accessibility.
3. Change the sheet names in the first line to the ones you want to delete.
4. With the document open click the triangle 'run' button.

Be sure to make a backup of your document first.

SG

set sheetsToDelete to {"Sheet 1", "Sheet 2", "Sheet 5"}

tell application "Numbers" to tell front document
	try
		repeat with s in sheetsToDelete
			delete sheet s
		end repeat
	end try
end tell