A computer Hard Drive is a storage device used to keep all your data, even if the computer is powered off.
Removing a Hard Drive from a Laptop is a relatively straight forward process to do, in may cases it only involves removing a few screws from the bottom of the case to get inside and extract the hard drive.
So, does removing a hard drive from your computer remove all the data? No. Data is stored on a computer hard drive in a format of 1’s and 0’s on magnetic platter inside sections called sectors.
Power is needed for the hard drive to move the reading/writing heads across the platters to access the sectors of information.
When there is no power going through the hard drive, the heads cannot move and thus cannot touch the sectors of 1’s and 0’s. Without power, the 1’s and 0’s will remain as they are on the hard drive, unchanged since it was last powered on so it does not affect the hard drive data recovery process.