if you have all your keys, you can start locally a node. When the node is synced, deregister your pool with **cardano-cli** by submitting a transaction with a **deregistration-certificate** created by the command **cardano-cli stake-pool deregistration-certificate [...]**

You don't have to recover the funds you pledged because you never lost control of your funds : you still have the signing key of the pledge owner address, do you ?

If you want to transfer your funds, you can create a wallet on Daedalus or Yoroi, and submit locally a payment transaction to transfer your pledged ADAs to this wallet. Be careful : **sign the transactions offline**. 

Edited : gave more informations on the way to de-register a pool