23 The LORD had allowed those nations to remain; he did not drive them out at once by giving them into the hands of Joshua.

Read Judges 2:23 Using Other Translations

Therefore the LORD left those nations, without driving them out hastily; neither delivered he them into the hand of Joshua.
So the LORD left those nations, not driving them out quickly, and he did not give them into the hand of Joshua.
That is why the LORD left those nations in place. He did not quickly drive them out or allow Joshua to conquer them all.