To delete a bookmark navigate to the "Tracks" screen by tapping the menu icon at the upper left corner of the audio player screen (it looks like 3 stacked white lines) and then tap "Bookmarks". Swipe to the left on the bookmark you'd like to delete, tap the Trash icon that appears, and then tap "Yes" to confirm deletion.
If this does not solve the issue please visit the FAQ page on our website (AudiobookSTORE.com) for other possible solutions or contact support.