How can I learn drawing from scratch like a kid?

Take your pencil and practice drawing a few straight and curved lines, long ones and short ones. Don't worry about doing this right or wrong, it's just a warm up. Then draw a few round shapes like circles and ellipses, and try out loose shapes like lying eights. Vary the size and also vary the pressure of your pen.

1. Start with Basic Shapes: Just like children, start by mastering simple shapes like circles, squares, triangles, and rectangles. These are the building blocks for more complex drawings.
2. Practice Regularly: Set aside time each day to practice drawing. Consistent practice is key to improving your skills.
3. Draw What You See: Observe objects around you and try to draw them as accurately as possible. Pay attention to shapes, proportions, and details.
4. Experiment with Different Tools: Try drawing with pencils, pens, markers, charcoal, or digital tools. Each medium has its own unique characteristics.
5. Take Inspiration from Children's Art: Look at children's drawings to see how they simplify shapes and colors. Embrace the simplicity and spontaneity in their art.

Start from free hand drawing of basic straight lines,hortizontal lines,diagonal lines, circles etc in both the directions for few days once you feel confident enough to draw them with ease try to draw very simple legible diagrams and slowly increase your ability to draw scenery, in this way you can start from scratch and improve step by step to the level you require.