I am in the 1st sem of BE EC and planning to leave it to pursue architecture or interior designing instead. Is it a correct decision?

I would suggest you to pursue ECE, in case if you don't like the subject then pursue architecture.

EC is a good branch as it has more career prospects than interior designing. You can put efforts for 4 years and get into a good IT company, any manufacturing or PSUs. Architecture do have good future scope, but currently EC is better to continue.