LPT: If you wish to disappear/run off, you can notify police of your intention to do so as it's not illegal as long as you're of sane mind, an adult and not committing any crimes

This comes with the added benefit that when friends and relatives contact the authorities to declare you as missing, they will simply either be ignored or informed of your intention to dissappear. You can then continue living in peace, isolation, or whatever else you choose. The police only look for people who disappear out of concern for their well-being, if it is your choise to do it and demonstrate your soundness of mind by going to a police station and filing a statement, they won't care. Officers will probably run a background check in accordance with the local regulations regarding personal data, but once it is determined that you are not a fugitive of law or a danger to yourself or others, you will be free to go.

Note: This tip is true in the UK, most of Central and western Europe, Greece, Japan and Turkey, and is probably true for the US but local state laws and practices may vary (although there is no law explicitly prohibiting someone from disappearing as long as they pay their taxes). I have no knowledge of the relevant laws in other jurisdictions around the world. It's a prerequisite that you file an official signed declaration in whatever way your state makes it available stating your intention to disappear and your sane condition. Does not require verification from any officials, at least in UK and Greece.

Edit:

Edit 2: Some people have correctly mentioned that the EU Right to be Forgotten act applies to electronic information. I would like to note that I clearly remember reading that it also extends to one's right to disappear as long as they continue fulfilling their obligations to the state and persons under their care, but since I can find no source confirming that online, I have removed the mention of the Act from the body of my post.

Edit 3: since a lot of comments mentioned it by now, and apparently they feel so strongly about this that I have to add it to the post. If you wish to hide from police or police officers, you shouldn't go to the police station. I thought it was obvious but alas some people need everything spelled out for them.

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