It's the "Skip" function and it's part of the "Set" Menu. To set a memory channel to "Skip" requires seven different actions:One of the drawbacks of the menu-driven Yeasu (and other brand) transceivers is that it takes more than one step to perform almost any function. There is a lock-out-annoying-channel function in the 7900 (I can't remember the actual term used right now and the manual is in the van with the rig), but it takes more than one keypress. It might be possible to do it without looking at the rig with practice.
Not that big of feature to switch to old commercial gear. I think it's a bigger hassle to reprogram an old Motorola radio..Nuisance delete, one of the main reasons I use commercial gear for my ham stuff.
The Yaesu FT-90R had a nuisance delete feature, but it's the only ham rig I've ever seen that had it.