A Welcome Discount Code is not an Inheritance
Before we start deleting, we need to know what we are holding. You know the steps (your priorities), now meet the luggage (the data that actually makes up your digital footprint).
Although you realise that you don't need all this shit, and you've probably had a little think about what your priorities are (if you haven't, please do that), it can feel like a big fucking task to get started. Do you have to sort through all your notifications one by one? Or your photos? Or, ugh, emails?!

Before we start deleting, we need to know what we are holding. You know the steps (your priorities), now meet the luggage (the data that actually makes up your digital footprint). This can be a little difficult to imagine, so I'm going to use the metaphor of a traveller's backpack, because everything we're doing here is about lightening our digital load.
The Passport, Keys and Cards: Your Identity
This is the stuff you keep in zipped up pockets or handbags, and you definitely don't want strangers going through it.
In our digital realm, these are the permanent, or very slowly changing, and often very small, pieces of data. Your name(s), emails, passwords, logins, business/corporate/government IDs and numbers, all that sort of thing.
The Journals, Postcards, Souvenirs: Your Archives
The important documents and mementos from your trip. It might be a vaccination record, proof you got a visa when passing through a border, or a piece of art. Whenever I am travelling, this is always what my bag ends up being crammed with. Often, they are also the gifts for others, of something you saw or experienced which reminded you of them. Generally, these things appreciate in value to us over time.
Medical and government records are functional for us, but beyond that? We are one of the first generations to be able to bequeath our descendants snapshots of our journey - not random tourist tat from destinations they'll visit too, but our journey through time. Where previous generations could pass down a piece of this depending on their resources or luck, and indeed the luck of it surviving, almost everyone can create and transmit digital records and resources now.
Clothes, Train Tickets, and Coffee Cups: Your Logistics
The logistical stuff. Gets you on the trip, keeps you protected, but these things do have an expiration date - even if distant. Used tickets, worn out socks, leaky shoes or broken cables (It is always broken cables for me, though I did also throw out a pair of shoes in Hong Kong airport) are not useful. That doesn't mean some things can't move into your archives (those tickets, for example), but broken cables do not. While I was in the airport, I would have loved to repair those sneakers, but they didn't have a cobblers and I didn't want to carry them around for a week. It was OK for them to go. In data terms, these are items that have a specific purpose, for a specific time (notifications of various things, generally), but after that, transition to the below.
Rocks, Sand, and Old Paracetamol packets: The Detritus
For some reason, I will pick up rocks from beaches (nature's souvenir, right??), and sand will always find a way. If I need the paracetamol on a trip, I'm probably not looking for a bin for the empty packet at the same time. This is stuff that perhaps had a use at some point, but not anymore.
If you're lucky, this stuff is just the above after its expiration date. However, in the society we live in, this is more likely to be random shit that you don't care about and actively demands attention. This could be marketing fluff, emails about parcels (that you get notified about in an app anyway), app notifications about "items we think you'll love" or that someone is "going live" that you have never, never, EVER cared about.
This is my taxonomy of data that we control - not exhaustive, but good enough to live with.