How to prevent uTorrent from autolaunching at startup?
If you use the web app version - see this answer - https://apple.stackexchange.com/a/394352/5472
Those still using the app, this guide will solve the problem:
Stop uTorrent from Opening at Startup with Mac OSX - wikihow Instructions
The steps from the link are:

Open uTorrent
Click on uTorrent beside the &quot;apple&quot; and click Preferences
Click on General
Uncheck the box. Under Program Startup there are two options. Uncheck the second one that says Start uTorrent when Mac starts up

This stops the uTorrent app launch the next startup.