Memory flasher

The memory Flasher, also called the Flash Gun or simply the Flasher, is a device used by the Legends and the Time Bureau to erase memories of individuals to keep history from altering.

History
After the Legends defeat the Legion of Doom and return Damien Darhk and Leonard Snart back to their own time periods, both of them have their memories erased using the Memory Flasher.

After escaping from Grodd and the Legends find Isaac Newton is still on board the Waverider, Mick flashes him before returning him to his own time.

After the Nazi invasion of Barry and Iris' wedding, Mick mentions that all of the wedding guests had their memories erased and everyone's secret identity remained a secret.

In the simulation that Zari was trapped in, Mick Rory is seen using the Flasher to erase a song stuck in his head. Amaya then takes the Flasher and uses it with Nate to erase their memories of making out on the Waverider. After Zari gets back to the real world, it's revealed that Nate and Amaya had actually been using the Flasher, to which Zari advises them that this was only a temporary solution.

Barack Obama was flashed several times, first to erase his memory of being attacked by Grodd, and a second time when Sara consults him for what to do about Mallus and the Time Bureau before erasing his memory of the conversation they just had. It's also implied that the senior Amaya had her memories erased by the flasher as she does not remember Nate.

Before Amaya is returned to her village in Zambesi, Nate planned on erasing her memories but Amaya requested she be allowed to remember them.