This is a fun thought experiment. If I’m understanding correctly, you’re writing a story where the character has a flash drive with important information. They have to remove the end to prevent the bad guys from getting access to it, then later replace the end to access the information themselves. Here’s my pitch (disclaimer: don’t actually try to do this. It would probably work, but if you have actual important files on a flash drive, this isn’t by any means how you should be trying to get at them)

For removing the end, soldering would be safe if they have access to a soldering iron. If it’s an emergency scenario, then I’d say just snap the plug off. It’s a bit risky depending on how the drive is made, but if it’s done deliberately by someone who knows what they’re doing, then I would say they could plausibly take off the USB connector without permanently damaging any of the guts.

For connecting the drive later, find a spare usb cable and cut it in half. It shouldn’t be hard to find one in an office. Even cutting the plug off a wired mouse or keyboard would work. Use a pocket knife or pair of scisors to strip the outer insulation off the cut end. This exposes four small wires. Strip the ends of those as well. Now, you just need a way of attaching each wire to the correct spot on the circuit board in the flash drive. Soldering would be best, but in a pinch, I’d look around the office for some of that sticky clay stuff they use to hang up posters. Pre-chewed gum might also work. Lay the stripped end of each wire over the correct spot on the board, then put a blob of the sticky stuff on top to hold it in place. Plug the other end into a computer, and you should be good to go.