Hibiscus yellow leaves and black spots

Hi all. I have a hibiscus which is approx 10 years old and readily flowers every year. I'm just getting into gardening properly, and realised last year that I needed to water it pretty much every day while flowering to ensure the flowers looked their best and provided plenty of nectar for the bees. So this year I decided to water it since early May to ensure it has a good start to the season. However, some of the leaves have turned yellow and have black spots on them. I guess I've over-watered it? Should I remove the affected leaves, particularly if the black spots are likely to be fungal?