There are two main considerations for this.
The first is how much do you need the money in the short term. If there is a chance of needing it then it is better to sell and keep what is left for any emergencies that come up.
The second is around your conviction in Tesla as an investment. If you believe it is going to be worth hundreds of millions in a few years then you should be looking to add to your position now, not sell. But it can be hard to fight the fear of a sharply dropping share price, this is where many people lose out on the big gains as they sell in fear at a low price and buy in greed at a high price.
If the first point doesn't apply to you, perhaps you should re-test your assumptions around the company and see if you still have the same conviction. If you do, take a Xanax and stay in.