Resetting the User Manager database in the Hotspot (2019) shows how to use the command line to completely erase the User Manager database from a Hotspot, and how to verify that everything has been erased.
For this tutorial, you will need one of the following Mikrotik routers:
Mikrotik RouterBoard RB951Ui-2nD hAP
Mikrotik RB3011UIAS-RM
Mikrotik Routerboard RB2011UiAS-2HnD-IN
Mikrotik RB750Gr2
Mikrotik hEX RB750Gr3
MikroTik RB2011iLS-IN
MikroTik Cloud Router CRS109-8G-1S-2HnD-IN
hAP lite
Hap
hAP ac lite tower
hAP ac
mAP lite
mAP
wAP RB951Ui-2HnD
RB951G-2HnD
RB2011UiAS-2HnD-IN
Mikrotik RB941-2nD-TC