As explained in the How do I erase all the existing timing? tutorial: you can "click the Wrench icon above the editing panel and select Clear timing item from the Tools menu. This will effectively take you back to the first stage.
However, if you just want to carry on translating, without losing the timing work you have already done, you can use the "Hide Timeline" option in the Tools menu that opens from the Wrench icon: see the Commands available through Tools menu (Wrench icon) tutorial. This will enable you to go on transcribing normally, without deleting the timing you have already done.
If I were you, I'd choose this second option: there are some timing issues in the subtitles you have already synced, but they could be relatively easily fixed once you've finished the translation.