CODE EXAMPLE FOR JAVASCRIPT

discord.js remove reaction

Since this question is getting a lot of attraction, I decided to post what worked for me

Remove Specific User's Specific Reaction

// Channel = the channel object of the message's original channel
// MessageID = ID of the message, if hard coding, put around quotations eg: "1234"

const msg = await channel.messages.fetch(MessageID);

msg.reactions.resolve("REACTION EMOJI, 
REACTION OBJECT OR REACTION ID").users.remove("ID OR OBJECT OF USER TO REMOVE");
Note: If using an older version of discord.js, simply replace channel.messages.fetch with channel.fetchMessage