It is just a register, like a phone book. But instead of names you have addresses and instead of phone numbers you have balances. if you throw your phone book in the trash nothing changes. The same people will still have the same phone numbers and in this case the bitcoin will remain on the same addresses as previously because they are not in your computer, they are on the blockchain. Therefore, you can have 1 wallet installed on one device or have it installed on 20 devices. All you have is 1 or 20 ways to explore this register.