House Training/Pee Pads

Question
My Australian Shepherd is turning 1 this week.  When I got him at 3 months, I used pee pads for him, but due to sickness, was not able to focus on training him and taking him out regularly to go to the bathroom.  He's been very good about using the pee pads.  I am now physically better and am trying to get him to go outside to do his deeds, which he sometimes does.  He urinates most of the time we go for walks and he's just started pooping on our walks, which is great.  But he still uses his pad inside and if I take it away, he goes to the bathroom where the pad would have been.  I've had days where I've taken him out 6/7 times a day and he'll go to the bathroom some of the time, but will also still uses the pad inside. It used to be at the point where there were days I'd walk him for a while, then when he'd go back inside the house, he'd go straight to the pad and pee!(at least he'll pee off the property now)

If I see him sniffing the pad, I immediately take him out, and I walk him in the morning, afternoon, and evening,  but throughout the night and while I'm at work, he'll use the pad, which I have to keep down because he'll go on the floor otherwise.  I know he's capable of "holding it in" because he's been able to do that when he slept in a crate for a couple of months when I first got him, and he was just boarded for a week and was able to hold it there. And I realize up until now, he was able to go on the pads whenever he wanted and didn't have a strict schedule or have any need to hold it in.

I know my lack of training and consistency with him has caused this problem, and I'm thankful he's still good about going on the pads if he is going to go inside, but I'm hoping there's still a way I can teach him to go outside only.

Thank you for your time.  I look forward to your response.

Answer
You sort of answered your own question.  The solution is to remove the pee pads, but crate the dog when you cannot directly supervise him indoors.  In other words, get him in the habit of always going outdoors now by temporarily restricting his freedom in the house.
Also, you need to clean the spot where the pads were with an enzymatic cleaner, such as Petastic, Simple Solution, or Nature's Miracle, so that there is no residual odor that the dog can detect.