I just did this today, very easy. On my 2007 I didn't have to remove the grill, just the top 4 screws. The grill will hinge out. Clip off the speed nuts, they will not pull off backwards. Save them and push the clipped off stud through so u can use them again or just get new ones.
On my truck the front emblem had no glue on the back of it, whew! So it popped right off once the speed nuts were off.
The rear emblem needed fishing line to cut through the glue, but it did not have speed nuts. Once popped off, lots of goo gone and a paint scraper to clean up the mess.
Install new emblems :)
I've never seen other ford emblems get ruined so quick, not sure why ours seem so prone to discoloring so quickly.
2007 XLT 4.0L Super Cab 4x4