Getting harder and harder to find old style circular lighting. I need to switch over to LED finally. Question is - Does the old ballast with starter remain or needed?

It depends. 

This video shows the differences.

(I just had a short look at the video, and it shows the principle)

 

 

for circular ones, most of the guts of the old lights need to be removed, starter, ballast and even the clip holding up the tubes, as the led panels is usually need flat metal back for the magnet to attach to

I had to replace a circular fluorescent light that had blown so I used a L.E.D. replacement.  
Similar to this:
LED CIRCULAR MODULE NAGAS CEILING MODULE MR 20W WARM WHITE (homepro.co.th)

Easy to install.
 

How to replace fluorescent tubes with LED tubes

1. Switch off the electric current.
2. Remove the ballast and the starter.
3. Replace the fluorescent lamp with the LED.
4. Connect the power and turn on.

12 minutes ago, OneMoreFarang said:

It depends. 

This video shows the differences.

(I just had a short look at the video, and it shows the principle)

 

 

I have the circular lights to switch over but the video does show the basics regardless of bulb style. According to this you'd remove entire ballast and just have power going directly to bulb.

13 minutes ago, digbeth said:

for circular ones, most of the guts of the old lights need to be removed, starter, ballast and even the clip holding up the tubes, as the led panels is usually need flat metal back for the magnet to attach to

I had a closer look at the new bulb and sure enough.....magnets, huh. 

I have more difficulties than you because I go and change all LED and fluorescent light fittings for incandescent, filament bulbs in the property where I live.  Have you ever tried to buy filament bulbs nowadays?

 

Why?

 

I swap over the lights because fluorescent and LED lights generate electrical interference - they cause havoc with my amateur radio hobby!  Maybe you remember a thread I posted a few years ago where I disconnected the LED street light outside my home?  That almost ended in disaster when the wooden ladder I used broke due to termite infestation and I fell 3 metres onto concrete, breaking several ribs and my cheekbone. The interfering light was 'gone' for a couple of months until the electricity company spotted that the wires had been cut (I denied knowledge of this and told them that a panicking owl had broken the wires!!)

I tell you what - once I switched over to LED there was no going back.  Better lighting; lower power consumption; lower cost to operate. Higher initial cost, but you make that up with lower electricity bills.

1 hour ago, simon43 said:

I swap over the lights because fluorescent and LED lights generate electrical interference - they cause havoc with my amateur radio hobby!  Maybe you remember a thread I posted a few years ago where I disconnected the LED street light outside my home?  That almost ended in disaster when the wooden ladder I used broke due to termite infestation and I fell 3 metres onto concrete, breaking several ribs and my cheekbone. The interfering light was 'gone' for a couple of months until the electricity company spotted that the wires had been cut (I denied knowledge of this and told them that a panicking owl had broken the wires!!)

"I fell 3 metres onto concrete, breaking several ribs and my cheekbone."

Consider that "Instant Karma" for destroying public infrastructure.

I don't think you have to remove the ballast, just the starter,

Our builder removed the lot, just two wires coming out of the ceiling, then screwed the new led light unit up, connected the wires, and finished.

The fluorescent light fitting plastic covers on the ceiling of my kitchen, have often dropped damaging the covers, and replacements cannot be found. If I replace with LED fittings I need something to cover the  area where the old fitting was fixed.  Diameter about 32cms, otherwise I have holes to fill and repainting to do/..Any suggestions?

3 hours ago, prakhonchai nick said:

The fluorescent light fitting plastic covers on the ceiling of my kitchen, have often dropped damaging the covers, and replacements cannot be found. If I replace with LED fittings I need something to cover the  area where the old fitting was fixed.  Diameter about 32cms, otherwise I have holes to fill and repainting to do/..Any suggestions?

Why not buy a new assembly large enough to cover the existing holes?

Oh, and the covers don't drop, they're dropped...