Electrical – How to remove this fitting from hard wired dishwasher

Green and bare wires are always ground. Ground is a means of short circuit protection, and all metal parts in electrical systems and fixtures are grounded. If a hot wire shorts out and touches the enclosure for some reason, it flows to ground and the circuit breaker/fuse trips (typically this happens in nanoseconds).

Without ground, if there is a short, the metal parts become energized. Once you touch it, you form the path to ground and get electrocuted.

Old fixtures didn't always have this, but we got smarter after several electrocution deaths. Modern fixtures without exposed metal (eg made of plastic) or where any metal is mechanically insulated from the wiring may not have ground as well. Since this is meant to be hardwired, they won't have spent the time to make sure everything is isolated correctly, so absolutely it needs to be grounded.

So no, you should not just cap the ground off, you should get a new wire that includes a ground. If you are leaving the wire exposed (not in any walls), you would typically use SJO wire (aka "extension cord wire" -- which is flexible, and has all conductors in a round outer jacket) in this situation. Readily available at any hardware stores.

You'll also need a surface-mount junction box of some sort, with the SJO wire terminating into it through a strain-relief connector of some sort.

There may be an in-ceiling connector as well as the connections which are certainly in the tape, but if you cannot pull a connector down by gently pulling on the wires, and if you cannot access the ceiling space, then the following will work.

(1) BEST: Get somebody competent to assist or to do the job - you have less chance of dying that way.

Otherwise:
(2) The red and white wires provide power. Presumably this is AC mains - you did not say what the supply is but if the bulbs are 110V or 230V rated then mains AC is what is involved.

Mains voltage is, of course, capable of delivering a lethal shock - I know you know that but a reminder does not hurt.

Connection is made to the blue and brown wires inside the tape. If the person who did it was half competent they will have used a very compact joiner or will have soldered the wires together, but it is likely that they are just twisted together.

Ensure life insurance is up to date.
Ensure house insurance is up to date and that you are prepared to accept the worst case outcomes - eg house burned down, You or others dead.(Unlikey, but always be aware).
Then.

Turn light off then on with usual switch - now you know the switch works.
Leave the light ON.

Turn off circuit to light at switchboard so light goes out.
ie Turn off circuit breaker or remove relevant fuse. Light is now OFF.

NOW turn off light at usual switch.
You now have two off switches. in series.

Tell everyone to not switch ANY light switches or power points. Your life just may depend on this.

Assume that there is AC mains power at light - there MAY be.
I have experienced AC mains present on a light socket under the conditions described above. Really!

Remove tape, assuming that either wire MAY be alive.
Red wire should be most likely to be live / Phase BUT no guarantee.

If wires are twisted together pull apart.
If a connector is used, discoinnect.
If soldered, unsolder or cut wires near to join in a manner which will allow you to rejoining OK. Using a connector - even a screw down "chocolate block" is preferred when reassembling. There is ample room for it in the ceiling space shown.

The unconnected green and yellow wire is for the earth wire that the lamp manufacturer thought that you should use but which the wiring person decided you did not need.

IF soldering with an earthed soldering iron be aware that either wire COULD have mains voltage potential relative to earth.

Option (1) should be loooking more attractive.

Report back - inquiring minds want to know.