Can i reapply for a CoE?

I was recently planning to migrate to Tokyo around April just before the lock downs began worldwide. I had done the Certificate of Eligibility (CoE) application for an Engineer visa but now realise that I could have instead applied for the Highly skilled Foreign professional (HSFP) visa which I am easily eligible for. I have received my COE but havent yet applied for a visa due to border closures etc. My main questions are:

1) Is it possible to reapply for a CoE for the HSFP visa despite having a valid COE for an Engineer Visa ? If not, can i cancel the latter and reapply ?
2) Any idea if its possible to switch to HSFP visa from an Engineer visa after moving to Japan ?

I see that the HSFP visa has several benefits such as the points based Permanent residency ( 1 to 3 years) which the Engineer visa doesn't (have to wait 10 years !!). Hence am very keen to change at this stage itself if possible.

Many thanks for your guidance.