Goodwill written off

Yes. One has to derecognise goodwill as per IndAS 110. This is in the case of full loss of control, the cost of investment will be credited. But if you, say I sold  40% equity but still it is a subsidiary, then

in the parents books you have to subtract Cost of investment in subsidiary from the sales proceeds

Sale proceed xxx

Less cost of investment in S xxx*40%

So, the treatment differs when a subsidiary becomes an associate, JV or completely sold.

So if you can confirm me if complete subsidiary was sold, I can give you the

Para 25(a) - Goodwill to be derecognised.

getdocument (mca.gov.in)

That means subsidiary shares were never sold to anyone. Goodwill can be impairment tested. If you still hold investment in subsidiary, no need to derecognise goodwill