My initial comment here is that I have actually done this. What I have done will be different than for you but the principles that I express here will be helpful.
First you need to understand what the person was using as their main points of identity. In a world of two-factor identification, this is important to start closing accounts online. Apple or Microsoft or Google and perhaps Facebook are what I would consider the usual suspects. (Leave these accounts for last.) Also, knowing the PIN to get into a person’s cell phone is a must. Typically, this is a four-digit number.
Banking and Money
Start with financial stuff. Freeze the debit or credit cards. Close any accounts tied to a person’s bank. Amazon, PayPal, Venmo, eBay, etc. You don’t want anyone draining the bank account while you are doing other things.
Please note that bank accounts can create terrible experiences for spouses, trustees, and relations. Financial institutions will often freeze accounts, want to see a death certificates, and be made aware of a clearly defined successor to any accounts. My wife and I have a Trust and that removed a lot of obstacles in this area. My former next-door neighbor let her husband handle all the bills and when he died, the banks and credit cards froze all the liquid assets. She went over six weeks just to get control of her checking account. Meanwhile, no bills could be paid, and she couldn’t buy any food.
Subscriptions
Cancel subscription services: Netflix, Disney Plus, Discovery Plus, Max, Kindle, etc. Do this even if you want to keep them. Redo any streaming accounts in the name of a living person.
Photos, Documents, and the like
Once you close the financial accounts, you need to start unwinding the stuff on the cell phone. Archive photos, email, text messages, documents on the phone. Also, check the “cloud storage” from Google, One Drive, Dropbox, Apple, etc. Put what you want to keep on a PC or laptop. To access Android data, you can set up Blue Stacks on your computer. Then you can access copies of photos, text messages, contact lists, etc. It takes patience and computer skills to do this.
Concerning text messages, they can be backed up and copied to a PC; however, they are completely unreadable without restoring them to another cell phone or using third party software. I can see them in Google Messages via Blue Stacks but can’t print them, which is really frustrating. I found third party software that can print them but the text message file from my wife’s phone was over 4 GB, and the software can’t handle such a large file without crashing.
The easiest account to close was Facebook; however, it takes some thought and preparation before you act. First you need to decide if you want to delete the account or have Facebook archive it. Either way, the contents of the account can be downloaded. This includes all photos posted, friend lists, and other stuff. Deleting the account is easy but there is another option. You can give control of the account to someone else. In the bowls of Facebook settings, it is possible to designate anyone on the friends list as a beneficiary. (Of course, FB calls this by another name.) The designated person can then go to their Facebook account and report that the person died. Before doing this, you will need a scanned copy of the death certificate. Fill out a simple form, again buried in the bowls of account settings, and be sure to attach the death certificate.
Reporting the death of a Facebook person and subsequent approval will lock the deceased person’s account, archive the account, and affix “In Memory of…” to the top of the FB page. This also givs the beneficiary control of the account. The beneficiary can post on the account, back it up, or delete it.
Root Accounts
There is a good chance that all or some phone data is backed up on Google, Microsoft, and/or Apple servers. Deleting these primary accounts will end any hope of data recovery. Use a tech savvy person to do this and then do a factory reset to the phone.
Final thought, Samsung no longer has their own cloud storage; instead, they piggyback it onto Microsoft’s One Drive. I am not clear if this is a stand-alone backup or part of the disk space allocated to Samsung users. Without a valid email account, you may not be able to access the data anyway. If you are extra paranoid, keep this in mind.
Have fun doing this. It took me a week and I’m not totally done, just at a comfortable place to stop … for now.