The manual says
2. Discard to obtain coins
You discard the card and take 2 coins + 1 coin per yellow card in your city from
the bank. The money is added to your city’s treasury.
The discarded cards are placed face-down next to the board. Players are free to
consult the discard pile at any point.
Example: Bruno discards the Aqueduct.
The explanation makes me confused. Do i discard the card from my cards list? or discard it from the center cards?
The card you just took.
rules page 10 which you're quoting from wrote:
You can play the card you’ve chosen in one of three different ways:
• 1. Construct the Building
• 2. Discard the card to obtain coins
• 3. Construct a Wonder