If you haven't read part 1 of this tutorial yet, you should read it first.
Swapping between two tokens
There is two ways of swapping tokens, using an already created liquidity pool or multi-hop swap. Multi-hop swap will cost more, but it will allow swapping two tokens that don't already have a direct trading pair, but there exists another token that has trading pair with either the base token or the destination token.
When using either method, the base token must be enabled like when creating the liquidity pool or adding liquidity. If for any reason the enabling fails, the swap can't continue. This is usually caused either by rejecting the approval transaction or error in the token contract. Trying to enable swap for larger amount than available balance can also cause enabling or swapping to fail.
Swapping between two tokens that have a liquidity pool will cost about 141442 gas (0.00070721 BNB).
Multi-hop swap using three tokens will cost about 212505 gas (0.001062525 BNB).
Removing liquidity from liquidity pool
Removing liquidity from a liquidity pool will convert the liquidity pool tokens to matching share of accumulated liquidity provider fees to balances in base and destination currencies.
It will move the liquidity pool tokens to the router contract and burn them, followed by sending share of the liquidity provider fees of both currencies along with the removed liquidity to the user wallet.
Transferring the liquidity pool tokens, and burning them will cost about 2300 gas (0.0000115 BNB), and removing the liquidity will cost about 33035 gas (0.000165175 BNB).