Start with where your data actually is, because that determines how you get at it.
Your identity: export it yourself from your settings at uiid.me. You can export your full identity as a .uiid file, or export a single alias on its own. No request needed.
Your aliases: deleting an alias purges it from the network entirely, including every data node stored under it. If an application kept your settings or profile there, that goes too. Your Core ID is unaffected.
One caveat on deletion: a key marked immutable by an application cannot be removed by you directly, and it blocks full account deletion until the application provider removes it. Use request-deletion to notify them.
Your whole identity: a UIID can be deleted completely, from your settings. Read the warning first — deletion is one-way, and the mechanisms that prevent duplicate identities may prevent us issuing you a new verified one.
Data inside a community you joined: that belongs to the network's operator, not to us. Ask them.
Where your data sits: for European users, in Germany or elsewhere in the EU, because LINKSPREED UG serves the European market.
Formal requests and the full policy: http://legal.linkspreed.com, or write to [email protected].