I remove the leaves and throw them in the trash can. Try not to get water on the leaves. I know you can't stop the rain from getting on them. I never sprayed mine and they were fine.

Yes remove leaves and I also rake them and use well composted mulch that does not breed disease. Soap is used to smother insects on leaves.

Grandma threw the dishwater on her roses to kill aphids. Nowadays dish detergent is much stronger and I've known folks who burned all the foliage off their roses by trying that old trick. Spraying aphids with a strong stream of water from a garden hose works much better.

How to control blackspot depends greatly on where you live (some areas have much higher BS pressure & different BS strains than others) and the type of roses you grow (some roses are more susceptible to BS than others).

Spraying them with a fungicide on a regular basis is the best way to eliminate BS. However, many of us have decided that we don't wish to use those harsh and dangerous chemicals in our gardens anymore so we've begun to use less hazardous methods. Removing the spotted leaves is one of those. But be careful with that too. If a leaf is still green it is still capable of producing food for the plant. And that plant will need energy to produce new leaves. I only remove the already yellowing leaves as those will no longer supply energy anyway.

Removing the leaves will not eliminate the BS. It just slows it down a bit. The spores for it are already out there everywhere. They are in the plants, in the soil and in the air and only need the right weather conditions to become active and spread through your roses. They particularly like cool wet nights which is why they tell you not to water late in the day. it doesn't give the plant enough time to dry off before it cools down and gets dark. That can't always be avoided though. It's pretty much a never ending battle and unless you want to spray constantly you really need to adjust your expectations some and learn to live with some spots. It doesn't make the blooms any less beautiful!

Soap water will not help with Blackspot...