any limitation to use "bitcoind - zapwallettxes" to reverse unconfirmed transactions?
Run bitcoind and with -zapwallettxes.


bitcoind is the daemon version of the original Bitcoin wallet maintained by Bitcoin Core. bitcoin-qt would be the GUI version.

The option -zapwallettxes is specific for the Bitcoin Core wallet. It 'forgets' spend outputs and allows you to respend them. However this does not imply that other bitcoin nodes on the network accept a new transaction with the same (already spend in your first transaction) outputs. 

-zapwallettxes is only affects your local wallet.

Your transaction can not be reversed. Probably the best thing to do is wait. Your transaction will confirm eventually.