You should have a look at this thread from the official LiteSpeed forum: https://bit.ly/345zzBc
If you believe you are NOT using LiteSpeed Cache and it is NOT installed as a WordPress Plugin, then you are most probably running a Shared Server that is running some LiteSpeed version in the background which is adding the X-Turbo-Charged-By: LiteSpeed header because you are also using a CDN (Cloudflare in this case). The aforementioned forum thread has more info about the issue.
Now, I’m really wondering why you want to remove that header? If it has no performance impact on your server, I wouldn’t put too much effort in removing it.