Xiaomi
Remove a Contact from Speed Dial auf Xiaomi
Speed dial on MIUI lets you assign a handful of contacts to number keys for one-tap calling. Once all slots are occupied, the Phone app will not let you add a new entry until you clear one manually.
The shortcut lives inside the advanced call settings, separate from your regular contact list, which is why deleting a contact from your address book has no effect on it. To free up a slot, open Open the Phone app ➔ Open the Settings ➔ Tap on Advanced settings ➔ Tap on Quick dial, then select the assigned number you want removed and confirm with Tap on Delete.
Only the quick dial link disappears. The contact itself stays untouched in your phonebook and keeps its saved number, call history and messages.
If you actually want to get rid of the person entirely, you need to delete the contact separately from your address book afterward. Removing just the speed dial slot is the right move whenever you only want to swap in a different number for that key.