If I drop from my architecture studies in ETHZ Zurich, can I restart in Manchester? I think about studying architecture in ETHZ Zurich (Switzerland), but due relatively high student dropout I have certain concerns if I would manage to go through.

Assuming I fail the necessary exams enough times to be asked to abandon studies, would it be possible then to try exactly the same (or closely related) subject in another leading university like Manchester University (United Kingdom)?

If the details are important, the details are Europe, ETHZ, Manchester University. If the answer can be generalized somehow, this would be obviously great.

I am aware that if I drop from ETHZ I cannot restart studies any relative discipline there. I am not sure however is it just an ETHZ specific internal rule or some unwritten rule with potentially much wider coverage.
The question can only be answered by an admissions committee at Manchester. But, like any other application, you need to show them that you are a good candidate to succeed in the program and afterwards. There is competition for any available slot and they want to make the best choices. 

A series of failures isn't a great endorsement. If you want to move, do so before the situation looks hopeless. 

However, there is an exception to the above. If you fail the exams for some odd reasons other than lack of preparation and diligence, then you might be able to have some professor speak highly enough of you that an admissions committee will make an exception. This is especially true if the professor has some personal or professional relationship with people on the receiving end. 

But an anonymous student with a poor record isn't likely to be an obvious choice for acceptance.