Depending on the original purpose of the board that you will be using, the components that will be on the board will differ widely.
Mine came from a printer, and there were a lot of through-hole components that I didn’t want in the final pendants. These included capacitors, coils, resistors, and some external connectors that I first removed.
If a certain component was higher than 2~3mm I removed it.
To remove the components, I first added flux to the joins and some fresh low melt solder. This way, I was then able to more easily remove the components by heating their legs and gently pulling from the other side.
Some of the connectors that had multiple pins were more difficult to be removed and I had to use my hot air soldering gun so I can heat the multiple pads at the same time.
If you don’t have a hot air gun, then you can cut the connector off, but this way you won’t be able to reuse it.