Procedural Level Generation

In the picture, you can see i generated a grid of levels. I used a basic tutorial online https://www.youtube.com/watch?v=VmRggTwhiew (Sorry if youre not allowed to post links, not sure how to make it a drop down or anything.) My goal is to make it so in the middle of the grid, my persistent level will be. However, right now the grid generates a 6x6 grid. Theres a tile below my level in the middle. How do i make it so the levels are only generated around the level?