Hello,
We made it for you in next way
1/ Enabled Show Hierarchy switcher -> https://prnt.sc/9YxBR-JUknHF
2/ Added custom css -> https://prnt.sc/n0AafegyTRKl and 3rd level is hidden now -> https://prnt.sc/86e3Z4XTgG54
Clear your cache and check !
Regards