Removing liquidity from a pool is a two-step process. First, exit method creates a redemption request and adds it to Redemption Queue. The queue is processed automatically when users interact with the protocol and free collateral becomes available. Once that happens, the queued request is converted to Released Liquidity - an amount of collateral available to withdraw at any time. This can be done using withdrawReleasedLiquidity method.
Note: if enough free collateral is available when the request is made, then the entire process above happens atomically.