Someone has a remote access to my PC, how to block them?

I've experienced today a control takeover on my pc as i was doing my business, the hacker started typing chinese, opened a lot of windows, used the mouse. I've shut down the pc immediately and deactivated the WIFI. I've ran anti-malware scans but nothing to report here. I've digged into the event observer and with some internet articles, managed to find myself in the TerminalService - LocalSessionManager and discovered that a "defaultuser100000", a few minutes before the attack, launched the distant desktop service as i've undertood what i've read. See more here :

• <Event xmlns="**http://schemas.microsoft.com/win/2004/08/events/event**">
• <System> <Provider Name="Microsoft-Windows-TerminalServices-LocalSessionManager" Guid="{5d896912-022d-40aa-a3a8-4fa5515c76d7}" /><EventID>21</EventID><Version>0</Version><Level>4</Level><Task>0</Task><Opcode>0</Opcode><Keywords>0x1000000000000000</Keywords><TimeCreated SystemTime="2024-03-15T16:46:21.8921078Z" /><EventRecordID>6054</EventRecordID><Correlation ActivityID="{61a55000-55e5-1017-0000-000000000000}" /><Execution ProcessID="1152" ThreadID="1636" /><Channel>Microsoft-Windows-TerminalServices-LocalSessionManager/Operational</Channel><Computer>xxx</Computer><Security UserID="S-1-5-18" /></System>
• <UserData>
• <EventXML xmlns="Event_NS"> <User>DESKTOP-8BKLKN9\defaultuser100000</User><SessionID>1</SessionID><Address>LOCAL</Address></EventXML> </UserData>

</Event>

As it's not my username and my actual username appears clearly on other logs, i'm genuinely asking myself if i've spotted the guy. But something weird aswell is that it seems like at the PC start, a distant desktop session is opening ( i traduce from french but i read "Remote Desktop Services: successful login :" and "Remote Desktop Services: kernel startup notification received :" from my own username.

To sum up, i'm not suspecting a malware, it's there for sure but i would urgently need to know how to block any future remote access from the hacker. Thanks a lot!