Legobot manages quite a few different tasks, so in many cases blocking the bot is not the best option. Some tasks have an "off switch", which will be mentioned in the edit summary or down below. You can probably also stop the bot from trampling over a specific page using {{nobots}}. If you absolutely must, you can block the bot.
This user account is a bot operated by Legoktm (talk). It is a legitimate alternative account, used to make repetitive automated or semi-automated edits that would be extremely tedious to do manually. The bot is approved and currently active. Administrators: if this bot is malfunctioning or causing harm, please block it.
This bot runs on the Wikimedia Labs cluster. Administrators: If this bot needs to be blocked due to a malfunction, please remember to disable autoblocks so that other WMF Labs bots are not affected.
For most things, {{bots|deny=Legobot}} should work. If you wish to opt-out of GA bot notices, please use {{bots|deny=GA bot}}
If it keeps removing an RFC as expired that you wish to continue for whatever reason, add <!-- RFCBot Ignore Expired --> somewhere on the page. It's your responsibility to archive the RFC and remove the template once it is over.