Looking at the style Kevkev has on, the "key" is honestly just a specialized screwdriver. Most eternity collars that are cheap use a pin screw, actual lock mechanisms are rare and only at the higher end price range, and are generally viewed as a "why would you bother? This shouldn't even need to come off anyways" type thing. The really hardcore eternity collars need a special tool to crimp the metal, making it impossible to remove in a nondestructive manner, or are designed to shear the pin so it can't ever be removed. In the subculture these things are as serious of a commitment and as meaningful, if not even more meaningful, than a wedding ring for showing commitment, but unlike a wedding ring, it has the BDSM flair to it, so that means it's a bit more intense and is designed to be a weighty so you constantly feel what you are wearing, visible, and difficult to remove reminder of commitment. For our cooming Kevin, well, it's a meaningless accessory and part of his LARP.
Since we know there is at least the potential of a key, and this is the tranch, we can assume it is just a pin screw. If we're lucky then they need some weird specialty bit, like a seven pointed star of uneven spacing or something wacky, to remove the pin screw. The far more likely answer though is it is just a Philips, Robinson, blade, or Allen screw. The key is symbolic at best.
Unless a picture is out there of the key or the lock pin/mechanism, I am going to assume it is just a shitty cheap common pin screw.
I know of people who, due to whatever reasons, had a falling out with their dom and the only way to remove the collar was to cut it, and if its too tight that can be rough. It can also cause breathing and eating difficulties. Not only that, but if it is rubbing against you too much it can cause sores and other issues. To prevent such concerns there is something called the two finger rule, basically can you fit in two fingers? If not, don't put it on the sub. Period. If due to whatever reason things change and the rule is no longer true, remove it and replace it.
Since Kevkev is inflating he's likely going to have issues, and since he won't remove it so long as he's with mistrxss complications are likely in his future, and if it needs to be cut off it won't go over nicely. Though considering tranch, he'll likely just be able to get a common screwdriver off amazon to release him.
Just use some bolt cutters. It looks like its just aluminium, not steel. It'll be faster and you won't gunk up your blade.
