If you don't know, there is two skips. One is for The Pit Falls in level 0 and a skip for level 4 for jump out of somewhere.

LEVEL 0
Level 0 has a Pit Fall section of the level. If you find the Pit Falls section, look for black mold on the roof. These are normally and mostly above one of each Pit Falls. In each Pit Fall area you can only find one black mold on the roof of one of the pits in each Pit Falls area. Once you have found the mold, jump down the pit and you will be saved by mattresses. Once below the Pit Falls, find the line and where ever the arrows are pointing you go. TIP: Find soup, it is almost guaranteed that you see at least some soup below the Pit Falls.

LEVEL 4
Once inside Level 4 you come across many windows within the level. It doesn't matter which window you jump out of. The easiest way of getting out the window is climbing one of the tables near the window. You can climb the table and chairs by first sprinting while jumping onto the chair. When on the chair while sliding slowly, immediately start jumping onto the table. Once on the table, jump out the window near it. But if you cannot find a window near a table, then use the smaller desks. First start by jumping on to the desk by sprinting then jumping at the right time. Then (OPTIONAL) jump onto the thin wall part of the desk. Then proceed to jump out the window. Once you have jumped out the window, you should be teleported into the Pool rooms (level 37 i think). You entirely skip the next level after level 4 (level 6: LIDAR).

That is all you have to do to skip those two levels with ease. If you want to you can add rewards to this post but I recommend giving them to someone else. Have a great day.