Firstly if it started the motors and took off with out input from you via either touching the launch button or using the CSC stick position then I think it you need to be careful of this drone it may be faulty.
Secondly if it did not need activation then it it not new. (Did you buy it as new?) If it was new and needs activation then it should not take off with out being activated. If it did I would be wary of it.
Thirdly.
The normal method of stopping the motors of a drone held still/stationary in the hand is to hold the throttle closed, this should stop the motors after a few seconds. If the drone is fighting you then it may take longer as it first needs to sense that it is still/stationary before it will stop the motors.
There are two method of emergency shut down.
Ordered by ease of use the first, and not an official method, is to quickly tilt the drone to 90deg so that the propellers are vertical but this may not always work. The alternative needs you to go into the menus of the control app, find the emergency shut down option and change the setting to "Anytime". Then put the sticks into the CSC position and hold them there, the motors should stop after the position has been held for around 2 seconds.
Once the motors have stopped switch the option back to "Emergency Only", it is too easy to trigger a mid air shut down with the option left at "Anytime".
I suggest you read the manual before you make another attempt, I assume this is a
Mini 2 in which case the manual can be found at
pdf . (Click on the brown print of "pdf".)