To show only one row as per your business you have to check the Enable Conditional box in dimensions
mention the condition as if(1=1,0,1)
Then you have to go to expressions select the expression and check the No Totals button.
Then you will get the expected result.
PFA for refrence
Can I know what is the purpose of usgin the total in ur bar chart?
Do u want to use it with other measures(as a reference line?) alone (one bar represeting the total and basta?)
would it be static (independant of any selection? or depends on the selection? (the total of what u select)?
Please, provide the explanation of the desired outcome so that our help would respond directly to ur need