Sony Xperia 5 V 128GB - Silver - Unlocked

I was using an Xperia with an au carrier before I changed my phone, but the product I received was originally a docomo carrier and I received a notification that I needed a d-account to upgrade my phonebook etc. As for me, the unnecessary, pre-installed apps were from docomo and I wanted to delete them, but I couldn't do that either. I think the problem was that I did not know the original carrier information of the phone before I bought it in the first place, and only found out after I arrived and opened the box. However, I thought it would be OK because it was SIM-free and I had transferred the data from my previous phone, so even if I had it exchanged for an au carrier Xperia, would I continue to use it considering the hassle of transferring data and re-logging in to the apps? I'm not sure... It's a real shame because the product itself is very beautiful and works very smoothly.