Erase Data, previously known as Backup Clear in Super Smash Bros., is an option in the first three installments of the Super Smash Bros. series. It allows the player to erase any specific data in the game, such as high scores, trophies, unlockable characters, and unlockable stages. In all three appearances, the option to erase singular categories of data is available, alongside an "Erase All" ("ALL Data Clear" in Smash 64) option.
When the player erases all data (once "Erase All" is performed), then there is no way to recover it. As such, Super Smash Bros. Melee advises players to save a copy of game data onto a separate memory card. However, while that is possible in Melee, this is not possible in Smash 64 nor Super Smash Bros. Brawl. The game data is directly saved to the Nintendo 64 game cartridge for Smash 64 (without a memory card), and the game data cannot be copied from one Wii to another (nor to an SD Card) in Brawl.
Neither version of Super Smash Bros. 4 nor Super Smash Bros. Ultimate has an "Erase Data" option, making it impossible to selectively erase any specific data. Players for those three games Smash 4 and Ultimate (if both versions of Smash 4 are counted separately), can only erase all of it. In Smash 4, players can erase all game data by holding A, B, X, and Y on startup (on the 3DS in Super Smash Bros. for Nintendo 3DS or the Wii U GamePad in Super Smash Bros. for Wii U) and selecting "Yes" three times when prompted (just like in Brawl for "Erase All"). However in Ultimate, unlike Smash 4, there is no such built-in application. The player can erase all data by erasing its data file through the "Manage Save Data/Screenshots and Videos" section of "Data Management"; which is located under the "System Settings" of the Switch.