using var driver = new FirefoxDriver();

driver.Url = "https://google.com";

Console.WriteLine(driver.Manage().Cookies.AllCookies.Count);

driver.Manage().Cookies.DeleteCookieNamed(null);

Console.WriteLine("Deleted some cookie");

Console.WriteLine(driver.Manage().Cookies.AllCookies.Count);

23:51:41.636 DEBUG HttpCommandExecutor: Executing command: []: newSession {"capabilities":{"firstMatch":[{"browserName":"firefox","moz:firefoxOptions":{"binary":"C:\\Program Files\\Mozilla Firefox\\firefox.exe","prefs":{"remote.active-protocols":3}}}]}}
23:51:41.642 TRACE HttpCommandExecutor: >> POST RequestUri: http://localhost:59253/session, Content: System.Net.Http.ByteArrayContent, Headers: 2
{"capabilities":{"firstMatch":[{"browserName":"firefox","moz:firefoxOptions":{"binary":"C:\\Program Files\\Mozilla Firefox\\firefox.exe","prefs":{"remote.active-protocols":3}}}]}}
1733691103700   mozrunner::runner       INFO    Running command: "C:\\Program Files\\Mozilla Firefox\\firefox.exe" "--marionette" "-no-remote" "-profile" "C:\\Users\\Nick\\AppData\\Local\\Temp\\rust_mozprofilebv8PPM"
Read port: 59260
23:51:45.648 TRACE HttpCommandExecutor: << StatusCode: 200, ReasonPhrase: OK, Content: System.Net.Http.HttpConnectionResponseContent, Headers: 2
23:51:45.652 DEBUG HttpCommandExecutor: Response: (b112c4de-b81a-42ee-a2da-5e2cfe5b44e3 Success: System.Collections.Generic.Dictionary`2[System.String,System.Object])
23:51:45.657 DEBUG HttpCommandExecutor: Executing command: [b112c4de-b81a-42ee-a2da-5e2cfe5b44e3]: get {"url":"https://google.com"}
23:51:45.659 TRACE HttpCommandExecutor: >> POST RequestUri: http://localhost:59253/session/b112c4de-b81a-42ee-a2da-5e2cfe5b44e3/url, Content: System.Net.Http.ByteArrayContent, Headers: 2
{"url":"https://google.com"}
23:51:46.590 TRACE HttpCommandExecutor: << StatusCode: 200, ReasonPhrase: OK, Content: System.Net.Http.HttpConnectionResponseContent, Headers: 2
23:51:46.590 DEBUG HttpCommandExecutor: Response: ( Success: )
23:51:46.591 DEBUG HttpCommandExecutor: Executing command: [b112c4de-b81a-42ee-a2da-5e2cfe5b44e3]: getCookies {}
23:51:46.592 TRACE HttpCommandExecutor: >> GET RequestUri: http://localhost:59253/session/b112c4de-b81a-42ee-a2da-5e2cfe5b44e3/cookie, Content: null, Headers: 3
23:51:46.594 TRACE HttpCommandExecutor: << StatusCode: 200, ReasonPhrase: OK, Content: System.Net.Http.HttpConnectionResponseContent, Headers: 2
23:51:46.595 DEBUG HttpCommandExecutor: Response: ( Success: System.Object[])
2
23:51:46.605 DEBUG HttpCommandExecutor: Executing command: [b112c4de-b81a-42ee-a2da-5e2cfe5b44e3]: deleteCookie {"name":null}
23:51:46.606 TRACE HttpCommandExecutor: >> DELETE RequestUri: http://localhost:59253/session/b112c4de-b81a-42ee-a2da-5e2cfe5b44e3/cookie/, Content: null, Headers: 2
23:51:46.609 TRACE HttpCommandExecutor: << StatusCode: 200, ReasonPhrase: OK, Content: System.Net.Http.HttpConnectionResponseContent, Headers: 2
23:51:46.610 DEBUG HttpCommandExecutor: Response: ( Success: )
Deleted some cookie
23:51:46.610 DEBUG HttpCommandExecutor: Executing command: [b112c4de-b81a-42ee-a2da-5e2cfe5b44e3]: getCookies {}
23:51:46.610 TRACE HttpCommandExecutor: >> GET RequestUri: http://localhost:59253/session/b112c4de-b81a-42ee-a2da-5e2cfe5b44e3/cookie, Content: null, Headers: 3
23:51:46.612 TRACE HttpCommandExecutor: << StatusCode: 200, ReasonPhrase: OK, Content: System.Net.Http.HttpConnectionResponseContent, Headers: 2
23:51:46.612 DEBUG HttpCommandExecutor: Response: ( Success: System.Object[])
0
23:51:46.613 DEBUG HttpCommandExecutor: Executing command: [b112c4de-b81a-42ee-a2da-5e2cfe5b44e3]: quit {}
23:51:46.613 TRACE HttpCommandExecutor: >> DELETE RequestUri: http://localhost:59253/session/b112c4de-b81a-42ee-a2da-5e2cfe5b44e3, Content: null, Headers: 2
23:51:47.353 TRACE HttpCommandExecutor: << StatusCode: 200, ReasonPhrase: OK, Content: System.Net.Http.HttpConnectionResponseContent, Headers: 2
23:51:47.353 DEBUG HttpCommandExecutor: Response: ( Success: )