Through Decryption Window
To decrypt the file use the following procedure:
1. On Home screen, in ribbon menus, click 
Tools > click 
Data Encryption.
Tools > click Data Encryption. 2. The Data Decryption/Encryption Window appears.
3. Select Decrypt, and then click Browse to select the encrypted file.
Figure 69 : The Decryption/ Encryption Window
4. Click Decrypt, the decryption password window appears.
Figure 70 : Decryption Password Window
5. In Decryption Password Window enter the previously entered password.
6. At the bottom of the screen click OK, the Decryption/Encryption process completion window appears when the process ends.
Figure 71 : Decryption complete
7. The protection is removed; the decrypted file gets saved at the original location ,where your encrypted file was saved 
double click to open the decrypted file.