You want to customise the variable

org-agenda-skip-deadline-prewarning-if-scheduled

setting it to "Remove prewaring if entry is scheduled". (In a setq that would be the value t).

For example

* TODO something
  DEADLINE: <2018-03-16 Fri> SCHEDULED: <2018-03-14 Wed>

then appears in a weakly agenda as

Week-agenda (W11-W12):
Wednesday  14 March 2018
  k:          Scheduled:  TODO something
Thursday   15 March 2018
Friday     16 March 2018
  k:          Deadline:   TODO something
Saturday   17 March 2018
Sunday     18 March 2018
Monday     19 March 2018 W12
Tuesday    20 March 2018

You want to customise the variable

org-agenda-skip-deadline-prewarning-if-scheduled

setting it to "Remove prewaring if entry is scheduled". (In a setq that would be the value t).

For example

* TODO something
  DEADLINE: <2018-03-16 Fri> SCHEDULED: <2018-03-14 Wed>

then appears in a weakly agenda as

Week-agenda (W11-W12):
Wednesday  14 March 2018
  k:          Scheduled:  TODO something
Thursday   15 March 2018
Friday     16 March 2018
  k:          Deadline:   TODO something
Saturday   17 March 2018
Sunday     18 March 2018
Monday     19 March 2018 W12
Tuesday    20 March 2018

The possible settings for this variable are

• "Always show prewarning" (nil)
• "Remove prewarning prior to scheduled date" (pre-scheduled)
• "Remove prewarning if entry is scheduled" (t)
• "Restart prewarning N days before deadline" (integer)

These do not affect showing the deadline on the due date.