How to place a sell order on Kraken that only sells when the price stops going up? I can do basic buy/sell on Kraken fine using market and limit orders.
I'd like to place a sell order that will only sell if:

the price of BTC reaches a certain minimum amount
but, if the price keeps on going up, I of course want the system to wait until the price starts to drop again, say X %, before selling.

How can I do this?
At the moment, Kraken has disabled all advanced order types - so there is nothing that can do what you're looking for on Kraken.

That said, I think the order type that you are looking for is called trailing-stop-order.
You can read more about it here, for example: https://support.bitfinex.com/hc/en-us/articles/115003506545-Trailing-Stop-Order