hi Ivan- Assuming your dog is NOT suffering from separation anxiety, there are several things that you can do at the same time to solve this problem:
1. Like collieman and Jean said, confine your dog when you are not home. You can use a crate, I prefer to use babygates to section off a small part of the house, like the kitchen for example, so he has a bit more room to play with his toys by himself if he wants to. You can use the room he sleeps in, but it should be "puppy-proofed" - no things he can chew on that will be dangerous, like electrical cords, furniture etc. By confining your dog, you are preventing him from engaging in the unwanted behavior in your absence. (The more he practices the unwanted behavior, the more of a habit it will become.)
2. Leave your dog with safe things that he IS allowed to chew on. Hard chew toys, kongs for example, so he has some outlet to work his jaws and brain. No things that have small pieces that he can tear off and swallow (and possibly choke on), like squeaky toys.
3. One reason he is being destructive could be due to boredom or excess energy, and 7 months is where they are entering adolescence and will have very high energy levels. Before you leave your dog home alone, give him a good exercise, training, and play session to tire him out. Then when you are gone he will be more likely to sleep rather than go looking for things to do, and it will make confinement much more pleasant for him if he is already happy to spend the day sleeping. This is very important.
4. Other ways to work off his energy: put his meals in food-dispensing puzzle toys like kongs, buster cubes and similar toys, you can get these at petstores. And give these to him when you leave the house, like in his crate or in his puppy-proofed room, so it occupies him with something useful and fun when he is alone. And it helps work his brain so when he's done with the food-puzzle toy he will be less likely to be bursting with restlessness.
5. If you really can't put things out of his reach, you could try spraying bitter apple on them. You can buy bitter apple sprays at the petstores, it doesn't stain things, and it is non-toxic but it smells and tastes disgusting to most dogs so he will be less likely to want to put his mouth on them.
However, IF your dog is being destructive due to separation anxiety (meaning that your absence makes him panic and he "loses his mind" with anxiety and that's why he's destroying things because he can't control himself in his panic), then that's a totally different and more serious problem and requires different solutions. Symptoms of separation anxiety are if the destruction is centered around the doors (the dog is trying to claw his way out to get to you), or if the dog hurts himself in the process of destroying things and still keeps going, or if he also loses control of his bladder or bowels (but he is otherwise housetrained when you're at home), or if there is a lot of howling and crying and whining when you leave and continuing on when you're gone (your neighbors can tell you this, or if you just wait outside the door and listen), or if your dog becomes extremely anxious when you are about to leave. if any of these apply to your dog then a different approach to treating the destructive behavior is needed.