I need to disable my alarm on a 1997 bmw 528i.

Now im not sure since the manual says your model has the same alarm system as the 328i and on the 328i you can remove the module to disable by doing the following. you can unplug the control module. It is located under the glove box. Climb under the dash on the passenger side and remove a few screws on the trim panel under the glove box. Theres a black control module with a green connector. There should be a lock tab on the connector. press the lock tab and pull out the connector. The alarm should now be disabled. But if it has the special transponder key this may not work.
But if the only reason you want to disable it is because of the motion sensor setting of the alarm for no reason there is a solution for this. To disable the motion sensor, hit the lock button to arm, then hit lock button again within four seconds to disable motion sensor. Red light on rearview mirror should flash four times, then pause, then start flashing on regular intervals. this is most likely the reason if your having the issue where the alarm goes off every 20 minutes.
If you want to completely remove it below is a wiring diagram taken from the manual for you alarm system.
this is from the manual its the alarm wiring diagram.
Battery Constant 12v Positive Wire ( ): Red/White or RedBattery Constant 12v Positive Wire Location: Ignition Switch Harness
Starter Positive Wire ( ): Black/Yellow or Black
Starter Positive Wire Location: Ignition Switch Harness
Ignition Positive Wire ( ): Green
Ignition Positive Wire Location: Ignition Switch Harness
Second Ignition Positive Wire ( ): Purple/White or Purple
Second Ignition Positive Wire Location: Ignition Switch Harness
Parking Light Positive Wire ( ): Gray/Purple and Gray/Yellow. Use Both Wires. This vehicle has a dual parking light system that will require 2 extra relays.
Parking Light Positive Wire Location: At Headlight Switch
Power Door Lock Positive Wire ( ): White/Red
Power Door Lock Positive Wire Location: At Factory Alarm Plug. The alarm plug is a black 12 pin plug located just behind the glove box.
Power Door Unlock Positive Wire ( ): Blue/Red
Power Door Unlock Positive Wire Location: At Factory Alarm Plug. The alarm plug is a black 12 pin plug located just behind the glove box.
Door Trigger Negative Wire (-): Brown/Gray
Door Trigger Negative Wire Location: At Factory Alarm Plug. The alarm plug is a black 12 pin plug located just behind the glove box.
Domelight Supervision Wire: Turns On With Unlock
Domelight Supervision Wire Location: N/A
Horn Negative Wire (-): Brown/Red or Brown/Yellow
Horn Negative Wire Location: At Steering Column Harness
Tachometer Wire Negative Wire (-): Black
Tachometer Wire Negative Wire Location: At Instrument Cluster
Brake Light Positive Wire ( ): Blue/Red or Green/Red
Brake Light Positive Wire Location: At Switch Above Brake Pedal
Factory Alarm Disarm Wire (-): Disarms With Factory Remote Only. Factory Alarm Disarm Wire Location: N/A
Factory Anti-Theft System: Transponder Anti-Theft System, Requires Bypass And Extra Ignition Key. The 1997 model year vehicle may require a bypass module and an extra ignition key, if vehicle is equipped with a special key from BMW.
Factory Anti-Theft System Location: Transponder At Ignition Switch Tumbler
if you require further assistance please let me know and i will help assist you from there. Thanks, Midwest-Tek

My ignitoin lights somtimes wont come on when i try to start my bmw 328ci can you help me please thanks

If its a factory alarm you CANNOT.if its a clifford or another make GOOD LUCK...you will need the wiring diagram for the maker and believe me its not a job i would undertake...WHY....