Open your profile https://www.mql5.com/en/users/okane and click on Charts on the right side, find your chart, move mouse to the left corner on the chart and you will see Delete button
Are you sure that you uploaded? Because page should be opened with the chart if uploaded. And this feature works if your metatrader is connected with your username.
Anyway, you can write to servicedesk and ask them to find it if any.
"before I even opened a user from mt5"
it's very stupid the mt4 post personal work space including account number to mql5, but do not allow to delete !!
You registered 31 minutes ago here (and do not have any publications and any charts published) - your personal workspace is empty:)
No any account number was found (at least on my charts).
Profile - Charts - find the chart and delete it:
It's effectively possible to post a chart from MT4/MT5 without being connected to an mql5.com account.
So even if you connect or subscribe later, your chart is published but NOT linked to your mql5.com account, no way to delete it.
Example I just did. Doesn't appear in my profile, I can't delete.
If you lost the initial link, only way is to contact ServiceDesk.