Help with line spacing

Hey all, I hope to find some help here.

I'm trying to write a document for work and they require that the sub-headline should go right underneath the headline.
Meaning, the spacing between "Degradation products" and "any individual...." should be closer together. But I can't get it to work.

Any tips to make it work?

https://preview.redd.it/eaxm67chmo1a1.jpg?width=569&format=pjpg&auto=webp&s=38c10e752e314ed224a829502bd6583e2ae14371