How to demolish skyscraper?

There are 4 pillars on the front of the building which need to be destroyed. You can achieve this with RPGs, Tank shells, C4 and Missile emplacements. Also likely are Chopper rockets and IFV cannon, although I have not tested this.

The 4 pillars you need to destroy are the ones shown below. They already have some exposed reinforcement bars showing.

Each pillar takes 2x RPG shots to destroy, or 2x MBT rounds, or 2x TOW Stationary Emplacements or 5x C4 explosives. This be Beta values so this may change.

This is an "undamaged" pillar.

This is a "damaged" pillar.

This is a "destroyed" pillar. When all 4 look like this, it's time to GTFO.