Hello
How did you remove the local user? In case you thought it was gone after you switched user, meaning you didn't actually delete it, on the sign in screen, click on switch user, then for username, username should be:
.\localusername
Replace the localusername with the actual local username. This will switch you back to local domain and sign you into your original local user.
However, if you did explicitly deleted the local user, then try this:
Hold down Shift key while you choose Windows restart, then go to Troubleshoot > Advanced Options > Startup Settings, click on restart, then choose option 4.
When prompted for password, leave it blank and enter.
When you are in safe mode, hold down windows + r keys, type in netplwiz and press enter.
Then double click on your username, go to Group Membership tab, make it admin.
Restart, log back into your user. You should now have admin access.