How Can I Merge Polys along their common edge to form a single polygon?

For instance, I have a grid of four quads and I want to merge the two on the right side into one, eliminating the edge between them. The result would be a three polygon grid of two squares one the left and one rectangular quad on the right.

I had been just deleting the two polys then using "fill hole" to do this but there should be an easier way, right?

Thanks!