Encodes DelegationManager.undelegate(staker). Removes delegation and auto-queues all withdrawals.
Shares enter a 14-day escrow period (100,800 blocks) before they can be completed.

Nonce handling: The nonce is computed at call time. If you prepare multiple transactions before broadcasting, they will share the same nonce and only the first will succeed. Broadcast and confirm each transaction before preparing the next.