In the Zodiac versions, Cleanse is a White Magick 7 License that is found in a chest in the Cerobi Steppe's Terraced Bank. Cleanse can be used by three classes: White Mage, Red Battlemage, and Knight, although Red Battlemage and Knight can only learn it if they have the Espers Licenses—Red Battlemage through Shemhazai and Knight through Mateus.
In the original version Cleanse is a White Magick 5 License that costs 45 LP to learn, and 20 MP to cast. The spell is bought at the Phon Coast for 5,800 gil.
Bubble not only cures but prevents Disease, can be used by all four mage jobs, and can be obtained earlier, assuming the player is doing most available Hunts. However, it is not available to the Knight.