Web console does not allow to see or manipulate with Artemis transactions in prepared state.

This is useful if administrator must solve heuristic mixed exception by manually rolling back or commit transactions.

In CLI there are operation in messaging subsystem like:
list-prepared-transaction-details-as-html
list-prepared-transaction-details-as-json
list-prepared-transactions
rollback-prepared-transaction
commit-prepared-transaction

which can be used.