You can download Wandering Trader May Leave on CurseForge and Modrinth:
  CurseForge:   https://curseforge.com/minecraft/mc-mods/wandering-trader-may-leave
  Modrinth:      https://modrinth.com/mod/wandering-trader-may-leave
To keep a better overview of all mods, the issue tracker is located in a separate repository.
  For issues, ideas, suggestions or anything else, please follow this link:
    -> Issue Tracker
Because of the way mod loader files are bundled into one jar, some extra information is needed to do a PR.
  A wiki page entry about it is available here:
    -> Pull Request Information
Wandering Trader May Leave adds a simple way to ask the wandering trader to exit the map without resorting to violence. It adds a small button in the top left of the trade screen. When clicked, the trader disappears in a cloud of particles. You no longer have to kill it to get some peace and quiet.
The Trader Llamas disappear as well, but only if they are leashed to the trader. This behaviour can be changed in the config.
   All available config options:
despawnTraderLlamasToo  default true
If the trader llamas should be despawned alongside the wandering trader when pressing the button.
onlyDespawnLlamasWhenLeashed  default true
Whether the trader llamas should only be despawned if they are leashed to the wandering trader.
showDespawnParticles  default true
If particles should be shown when despawning the wandering trader and/or trader llamas.
/wandering-trader spawn - Accidentally made the wandering trader leave? Respawn it!
The command requires cheat access.
A little button is added:
Just click the button, and poof!
Show Spoiler
You may freely use this mod in any modpack, as long as the download remains hosted within the CurseForge or Modrinth ecosystem.
Serilum.com contains an overview and more information on all mods available.
Comments are disabled as I'm unable to keep track of them across so many separate mod pages.
For issues, ideas, suggestions or anything else there is the Github repo. Thanks!