After installing win7, drive c takes up more than 50 G, which is the pre-installed operating system of the computer itself. The solution is as follows:

1. First, find the computer housekeeper on the computer desktop and click, as shown below.

2. Then click the -Toolbox option below, as shown in the figure below.

3. Then on the toolbox page, find and click-System option, as shown in the figure below.

4, and then click the-system disk slimming option on the right side of the page.

5. Then click Start Scan. When the scan is complete, click Release Now.