Suggest you eat your biscuits and learn about how our system is set up. This petition has a perfectly plausible aim, were it to get enough signatures. (It won't, but that doesn't stop me signing in hope!)
The petition is to the queen. As head of state she does have the power to dissolve parliament. The PM is only there because the queen appoints him / her IIRC. In practice she always decides to appoint the winner of the general election but our law doesn't say she has to.
Dissolution of parliament by the monarch would usually happen after a vote of no confidence by a majority of MPs, but this is an interesting idea IMO.
What if people finally saw clearly what the tories are up and so say 30 million of us petitioned the queen to get rid of the tories. Would she do it?
(Not saying I think this will happen, but interesting to think what if)
We could argue for example that the Tory government has acted upon numerous policies that were not in the Tory election manifestos. These legislative changes therefore have no democratic mandate for implementation and could arguably represent a Coup d'état.
(I have copied and edited the last para from a similar petition for the last government)