You could use the same email address and ask. I would not be surprised if they say you can destroy it yourself, instead of sending it back.
Should I apply for new BRC ?
You don't have to, but you might find it useful for traveling, and proving your right to rent and work in case your electronic status doesn't show up (as has been the case of many people), while you obtain your British citizenship.
I am due to apply for citizenship in April 2022. The time it took to get my PRE Settle Status replaced took over 3 months. This make me nervous to apply for replacement BRC as I do not want to delay my Naturalisation Application.
You could do nothing, apply for naturalisation and explain in the form that you lost your BRC (they will ask why you cannot provide it). This is acceptable. But... it might take up to a year to become British Citizen and obtain a passport, so without a BRC you would be pretty much out of a physical proof of right to live and work in the UK for a while.
Or you could apply for a replacement. It might not be issued before you apply for naturalisation, but you can always explain that in the form. You do not need a valid physical BRC to apply for naturalisation, you do not have to wait for the new one to be issued.
Can I apply for citizenship just with my EU Settle Status Outcome email I received last year?
It's not the outcome email but your digital status that counts. But yes, you can apply with your electronic status.
You'll be asked for your reference number (the 16 digit code of your settlement application, then one of the form XXX-XXX-XXX-XXXX)
My posts express what I believe are the facts, based on the best of my knowledge, about the topics discussed in this forum. They do not constitute immigration advice.