• I have mikrotik l2tp VPN with 12 branch locations. each branch have two ISP connections and the main ISP connection connected to RB450 and use WAPR for Backup connection. I have configured VRRP for both routers and failover and other things working properly. each branch have 2 to 5 computers.

• Now I need advance option that means basic firewall for my Branches. I need to block internet for all branches without any desk, TeamViewer, Microsoft office 365, Microsoft Teams

How can I do that

Forward chain
Read about firewall rules etc. here.
viewtopic.php?t=180838

Get familiar with firewall rules as anav wrote, investigate services connections (ips/ip ranges and ports) which you need to allow (as I wrote you my example how I did this for QoS viewtopic.php?t=195989#p1006741) and block other.