Like all status effects, it can be removed by drinking Milk.
This status effect can only be gained from one source without the use of cheats, which is by being in close proximity to a Beacon with that particular effect activated.
The Efficiency Enchantment works in the same fashion as Haste does, as it allows the tool that it is put on to mine blocks faster than normal. However, this enchantment only affects the tool it is on, whereas Haste affects everything a player uses to mine while it is in effect.
As with other status effects, there is another status effect that does the exact opposite of haste. Mining Fatigue makes a player mine blocks slower than normal. It is obtained when a player is close to an Elder Guardian in an Ocean Monument.
When a player is underwater, they mine blocks slower than usual. While this isn't really a status effect, it does work in a similar fashion as the haste status effect does; however, a player cannot get rid of this effect at all unless they swim up to the water's surface.