I did it in steps. I run lawn and landscape crews.
First I got the lawn crew to a point where they could manage without me and i could trust they would do the job right.
Then I did landscape jobs with helpers and turned one of the helpers in to a foreman. When he was able to do jobs on his own then I would send him out with a helper.
At this time I started to spend about half the week out of the field doing estimates and administrative work. When I wasnt busy with that stuff I would go help on the landscaping jobs to reduce labor and help support my salary.
At some point I was able to add a second landscape crew and at that time I was able to be out of the field full time.
I now have 2 lawn crews and 2 landscape crews. It took me about 4-5 yrs to get totally out of the field.
Im sure some people can do it alot quicker, or if you have the funds and skills could probably start a business like this without ever being in the field.