Learn Spanish (Latin America): Para simplificar tu espacio, debes donar todo lo que acumules. - To simplify your space, you must donate everything that you accumulate.

We use the subjunctive (acumules) after todo lo que (everything that) because it refers to a future or undefined group of things. You aren't talking about specific items you have already accumulated, but rather whatever you might accumulate from now on. If you were stating a fact about things you already have, you would use the indicative: todo lo que acumulas (everything that you currently accumulate).

Why do we need lo in todo lo que? Can I just say todo que?

No, you can't skip the lo. In Spanish, todo que is incorrect. When everything that doesn't refer to a specific masculine or feminine noun, you need the neutral article lo to act as a placeholder. Together, todo lo que essentially translates to all that which or everything that.

Why use Para simplificar instead of Por simplificar?

Para is used here because it expresses a goal or purpose. When followed by an infinitive, para translates to in order to. Para simplificar means in order to simplify. Por would express a cause or reason (because of), which doesn't make sense in this context.

Could I use tienes que donar instead of debes donar?