Yes, you can likely cancel your KCET allotted engineering seat after completing 1 year,

The typical window to cancel or surrender KCET allotted seats usually closes after the second or extended round of counselling. Since you have completed year 1, you have missed that window.

The Karnataka Examination Authority (KEA) might impose a penalty for cancelling your seat after such a long period. The specific penalty amount can vary depending on the course you were allotted and the KEA's regulations.

https://engineering.careers360.com/download/ebooks/know-all-about-karnataka-cet-kcet

I hope it helps!