How to hide and lock formulas in Excel

non-adjacent cells or ranges by holding the Ctrl key, or the entire sheet by pressing the Ctrl + A shortcut.
To select all cells with formulas, use the Go To Special > Formulas feature as demonstrated in Selecting cells with formulas.

2. 
   Open the Format Cells dialog by doing any of the following:
   
   • 
     Press the Ctrl + 1 shortcut.
     
   • 
     Right-click the selected cell(s) and choose Format Cells from the context menu.
     
   • 
     Go to the Home tab > Cells group, and click Format > Format Cells.
     
3. 
   In the Format Cells dialog box, switch to the Protection tab, and select the Hidden checkbox. It is this option that prevents an Excel formula from being shown in the formula bar.
   

The Locked attribute, which prevents the contents of the cells from editing, is selected by default, and in most cases you'd want to leave it this way.

4. 
   Click the OK button.
   
5. 
   Protect your Excel worksheet by performing these steps.
   

Note. Please remember that locking cells and hiding formulas has no effect until you protect the worksheet (a short notice right underneath the Locked and Hidden options on the Format Cells dialog points to the next steps). To make sure of this, select any cell with a formula, and look at the formula bar, the formula will still be there. To really hide formulas in Excel, be sure to protect the worksheet.
How to remove protection and unhide formulas in Excel
To get the previously hidden formulas to show in the formula bar again, do one of the following:

• 
  On the Home tab, in the Cells group, click the Format button, and select Unprotect Sheet from the drop-down menu. Then type the password you entered when protecting the spreadsheet, and click OK.
  
• 
  Or, go to the Review tab > Changes group, and click the